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Article Contents

Introduction, physiological effects of dehydration, hydration and chronic diseases, water consumption and requirements and relationships to total energy intake, water requirements: evaluation of the adequacy of water intake, acknowledgments, water, hydration, and health.

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Barry M Popkin, Kristen E D'Anci, Irwin H Rosenberg, Water, hydration, and health, Nutrition Reviews , Volume 68, Issue 8, 1 August 2010, Pages 439–458, https://doi.org/10.1111/j.1753-4887.2010.00304.x

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This review examines the current knowledge of water intake as it pertains to human health, including overall patterns of intake and some factors linked with intake, the complex mechanisms behind water homeostasis, and the effects of variation in water intake on health and energy intake, weight, and human performance and functioning. Water represents a critical nutrient, the absence of which will be lethal within days. Water's importance for the prevention of nutrition-related noncommunicable diseases has received more attention recently because of the shift toward consumption of large proportions of fluids as caloric beverages. Despite this focus, there are major gaps in knowledge related to the measurement of total fluid intake and hydration status at the population level; there are also few longer-term systematic interventions and no published randomized, controlled longer-term trials. This review provides suggestions for ways to examine water requirements and encourages more dialogue on this important topic.

Water is essential for life. From the time that primeval species ventured from the oceans to live on land, a major key to survival has been the prevention of dehydration. The critical adaptations cross an array of species, including man. Without water, humans can survive only for days. Water comprises from 75% body weight in infants to 55% in the elderly and is essential for cellular homeostasis and life. 1 Nevertheless, there are many unanswered questions about this most essential component of our body and our diet. This review attempts to provide some sense of our current knowledge of water, including overall patterns of intake and some factors linked with intake, the complex mechanisms behind water homeostasis, the effects of variation in water intake on health and energy intake, weight, and human performance and functioning.

Recent statements on water requirements have been based on retrospective recall of water intake from food and beverages among healthy, noninstitutionalized individuals. Provided here are examples of water intake assessment in populations to clarify the need for experimental studies. Beyond these circumstances of dehydration, it is not fully understood how hydration affects health and well-being, even the impact of water intakes on chronic diseases. Recently, Jéquier and Constant 2 addressed this question based on human physiology, but more knowledge is required about the extent to which water intake might be important for disease prevention and health promotion.

As noted later in the text, few countries have developed water requirements and those that exist are based on weak population-level measures of water intake and urine osmolality. 3 , 4 The European Food Safety Authority (EFSA) was recently asked to revise existing recommended intakes of essential substances with a physiological effect, including water since this nutrient is essential for life and health. 5

The US Dietary Recommendations for water are based on median water intakes with no use of measurements of the dehydration status of the population to assist. One-time collection of blood samples for the analysis of serum osmolality has been used by the National Health and Nutrition Examination Survey program. At the population level, there is no accepted method of assessing hydration status, and one measure some scholars use, hypertonicity, is not even linked with hydration in the same direction for all age groups. 6 Urine indices are used often but these reflect the recent volume of fluid consumed rather than a state of hydration. 7 Many scholars use urine osmolality to measure recent hydration status. 8 , – 12 Deuterium dilution techniques (isotopic dilution with D 2 O, or deuterium oxide) allow measurement of total body water but not water balance status. 13 Currently, there are no completely adequate biomarkers to measure hydration status at the population level.

In discussing water, the focus is first and foremost on all types of water, whether it be soft or hard, spring or well, carbonated or distilled. Furthermore, water is not only consumed directly as a beverage; it is also obtained from food and to a very small extent from oxidation of macronutrients (metabolic water). The proportion of water that comes from beverages and food varies according to the proportion of fruits and vegetables in the diet. The ranges of water content in various foods are presented in Table 1 . In the United States it is estimated that about 22% of water intake comes from food while the percentages are much higher in European countries, particularly a country like Greece with its higher intake of fruits and vegetables, or in South Korea. 3 , – 15 The only in-depth study performed in the United States of water use and water intrinsic to food found a 20.7% contribution from food water; 16 , 17 however, as shown below, this research was dependent on poor overall assessment of water intake.

Ranges of water content for selected foods.

Data from the USDA national nutrient database for standard reference, release 21, as provided in Altman. 126

This review considers water requirements in the context of recent efforts to assess water intake in US populations. The relationship between water and calorie intake is explored both for insights into the possible displacement of calories from sweetened beverages by water and to examine the possibility that water requirements would be better expressed in relation to calorie/energy requirements with the dependence of the latter on age, size, gender, and physical activity level. Current understanding of the exquisitely complex and sensitive system that protects land animals against dehydration is covered and commentary is provided on the complications of acute and chronic dehydration in man, against which a better expression of water requirements might complement the physiological control of thirst. Indeed, the fine intrinsic regulation of hydration and water intake in individuals mitigates prevalent underhydration in populations and its effects on function and disease.

Regulation of fluid intake

To prevent dehydration, reptiles, birds, vertebrates, and all land animals have evolved an exquisitely sensitive network of physiological controls to maintain body water and fluid intake by thirst. Humans may drink for various reasons, particularly for hedonic ones, but drinking is most often due to water deficiency that triggers the so-called regulatory or physiological thirst. The mechanism of thirst is quite well understood today and the reason nonregulatory drinking is often encountered is related to the large capacity of the kidneys to rapidly eliminate excesses of water or to reduce urine secretion to temporarily economize on water. 1 But this excretory process can only postpone the necessity of drinking or of ceasing to drink an excess of water. Nonregulatory drinking is often confusing, particularly in wealthy societies that have highly palatable drinks or fluids that contain other substances the drinker seeks. The most common of these are sweeteners or alcohol for which water is used as a vehicle. Drinking these beverages is not due to excessive thirst or hyperdipsia, as can be shown by offering pure water to individuals instead and finding out that the same drinker is in fact hypodipsic (characterized by abnormally diminished thirst). 1

Fluid balance of the two compartments

Maintaining a constant water and mineral balance requires the coordination of sensitive detectors at different sites in the body linked by neural pathways with integrative centers in the brain that process this information. These centers are also sensitive to humoral factors (neurohormones) produced for the adjustment of diuresis, natriuresis, and blood pressure (angiotensin mineralocorticoids, vasopressin, atrial natriuretic factor). Instructions from the integrative centers to the “executive organs” (kidney, sweat glands, and salivary glands) and to the part of the brain responsible for corrective actions such as drinking are conveyed by certain nerves in addition to the above-mentioned substances. 1

Most of the components of fluid balance are controlled by homeostatic mechanisms responding to the state of body water. These mechanisms are sensitive and precise, and are activated with deficits or excesses of water amounting to only a few hundred milliliters. A water deficit produces an increase in the ionic concentration of the extracellular compartment, which takes water from the intracellular compartment causing cells to shrink. This shrinkage is detected by two types of brain sensors, one controlling drinking and the other controlling the excretion of urine by sending a message to the kidneys, mainly via the antidiuretic hormone vasopressin to produce a smaller volume of more concentrated urine. 18 When the body contains an excess of water, the reverse processes occur: the lower ionic concentration of body fluids allows more water to reach the intracellular compartment. The cells imbibe, drinking is inhibited, and the kidneys excrete more water.

The kidneys thus play a key role in regulating fluid balance. As discussed later, the kidneys function more efficiently in the presence of an abundant water supply. If the kidneys economize on water and produce more concentrated urine, they expend a greater amount of energy and incur more wear on their tissues. This is especially likely to occur when the kidneys are under stress, e.g., when the diet contains excessive amounts of salt or toxic substances that need to be eliminated. Consequently, drinking a sufficient amount of water helps protect this vital organ.

Regulatory drinking

Most drinking occurs in response to signals of water deficit. Apart from urinary excretion, the other main fluid regulatory process is drinking, which is mediated through the sensation of thirst. There are two distinct mechanisms of physiological thirst: the intracellular and the extracellular mechanisms. When water alone is lost, ionic concentration increases. As a result, the intracellular space yields some of its water to the extracellular compartment. Once again, the resulting shrinkage of cells is detected by brain receptors that send hormonal messages to induce drinking. This association with receptors that govern extracellular volume is accompanied by an enhancement of appetite for salt. Thus, people who have been sweating copiously prefer drinks that are relatively rich in Na+ salts rather than pure water. When excessive sweating is experienced, it is also important to supplement drinks with additional salt.

The brain's decision to start or stop drinking and to choose the appropriate drink is made before the ingested fluid can reach the intra- and extracellular compartments. The taste buds in the mouth send messages to the brain about the nature, and especially the salt content, of the ingested fluid, and neuronal responses are triggered as if the incoming water had already reached the bloodstream. These are the so-called anticipatory reflexes: they cannot be entirely “cephalic reflexes” because they arise from the gut as well as the mouth. 1

The anterior hypothalamus and pre-optic area are equipped with osmoreceptors related to drinking. Neurons in these regions show enhanced firing when the inner milieu gets hyperosmotic. Their firing decreases when water is loaded in the carotid artery that irrigates the neurons. It is remarkable that the same decrease in firing in the same neurons takes place when the water load is applied on the tongue instead of being injected into the carotid artery. This anticipatory drop in firing is due to communication from neural pathways that depart from the mouth and converge onto neurons that simultaneously sense the blood's inner milieu.

Nonregulatory drinking

Although everyone experiences thirst from time to time, it plays little role in the day-to-day control of water intake in healthy people living in temperate climates. In these regions, people generally consume fluids not to quench thirst, but as components of everyday foods (e.g., soup, milk), as beverages used as mild stimulants (tea, coffee), and for pure pleasure. A common example is alcohol consumption, which can increase individual pleasure and stimulate social interaction. Drinks are also consumed for their energy content, as in soft drinks and milk, and are used in warm weather for cooling and in cold weather for warming. Such drinking seems to also be mediated through the taste buds, which communicate with the brain in a kind of “reward system”, the mechanisms of which are just beginning to be understood. This bias in the way human beings rehydrate themselves may be advantageous because it allows water losses to be replaced before thirst-producing dehydration takes place. Unfortunately, this bias also carries some disadvantages. Drinking fluids other than water can contribute to an intake of caloric nutrients in excess of requirements, or in alcohol consumption that, in some people, may insidiously bring about dependence. For example, total fluid intake increased from 79 fluid ounces in 1989 to 100 fluid ounces in 2002 among US adults, with the difference representing intake of caloric beverages. 19

Effects of aging on fluid intake regulation

The thirst and fluid ingestion responses of older persons to a number of stimuli have been compared to those of younger persons. 20 Following water deprivation, older individuals are less thirsty and drink less fluid compared to younger persons. 21 , 22 The decrease in fluid consumption is predominantly due to a decrease in thirst, as the relationship between thirst and fluid intake is the same in young and old persons. Older persons drink insufficient amounts of water following fluid deprivation to replenish their body water deficit. 23 When dehydrated older persons are offered a highly palatable selection of drinks, this also fails to result in increased fluid intake. 23 The effects of increased thirst in response to an osmotic load have yielded variable responses, with one group reporting reduced osmotic thirst in older individuals 24 and one failing to find a difference. In a third study, young individuals ingested almost twice as much fluid as old persons, even though the older subjects had a much higher serum osmolality. 25

Overall, these studies support small changes in the regulation of thirst and fluid intake with aging. Defects in both osmoreceptors and baroreceptors appear to exist as do changes in the central regulatory mechanisms mediated by opioid receptors. 26 Because the elderly have low water reserves, it may be prudent for them to learn to drink regularly when not thirsty and to moderately increase their salt intake when they sweat. Better education on these principles may help prevent sudden hypotension and stroke or abnormal fatigue, which can lead to a vicious circle and eventually hospitalization.

Thermoregulation

Hydration status is critical to the body's process of temperature control. Body water loss through sweat is an important cooling mechanism in hot climates and in periods of physical activity. Sweat production is dependent upon environmental temperature and humidity, activity levels, and type of clothing worn. Water losses via skin (both insensible perspiration and sweating) can range from 0.3 L/h in sedentary conditions to 2.0 L/h in high activity in the heat, and intake requirements range from 2.5 to just over 3 L/day in adults under normal conditions, and can reach 6 L/day with high extremes of heat and activity. 27 , 28 Evaporation of sweat from the body results in cooling of the skin. However, if sweat loss is not compensated for with fluid intake, especially during vigorous physical activity, a hypohydrated state can occur with concomitant increases in core body temperature. Hypohydration from sweating results in a loss of electrolytes, as well as a reduction in plasma volume, and this can lead to increased plasma osmolality. During this state of reduced plasma volume and increased plasma osmolality, sweat output becomes insufficient to offset increases in core temperature. When fluids are given to maintain euhydration, sweating remains an effective compensation for increased core temperatures. With repeated exposure to hot environments, the body adapts to heat stress and cardiac output and stroke volume return to normal, sodium loss is conserved, and the risk for heat-stress-related illness is reduced. 29 Increasing water intake during this process of heat acclimatization will not shorten the time needed to adapt to the heat, but mild dehydration during this time may be of concern and is associated with elevations in cortisol, increased sweating, and electrolyte imbalances. 29

Children and the elderly have differing responses to ambient temperature and different thermoregulatory concerns than healthy adults. Children in warm climates may be more susceptible to heat illness than adults due to their greater surface area to body mass ratio, lower rate of sweating, and slower rate of acclimatization to heat. 30 , 31 Children may respond to hypohydration during activity with a higher relative increase in core temperature than adults, 32 and with a lower propensity to sweat, thus losing some of the benefits of evaporative cooling. However, it has been argued that children can dissipate a greater proportion of body heat via dry heat loss, and the concomitant lack of sweating provides a beneficial means of conserving water under heat stress. 30 Elders, in response to cold stress, show impairments in thermoregulatory vasoconstriction, and body water is shunted from plasma into the interstitial and intracellular compartments. 33 , 34 With respect to heat stress, water lost through sweating decreases the water content of plasma, and the elderly are less able to compensate for increased blood viscosity. 33 Not only do they have a physiological hypodipsia, but this can be exaggerated by central nervous system disease 35 and by dementia. 36 In addition, illness and limitations in daily living activities can further limit fluid intake. When reduced fluid intake is coupled with advancing age, there is a decrease in total body water. Older individuals have impaired renal fluid conservation mechanisms and, as noted above, have impaired responses to heat and cold stress. 33 , 34 All of these factors contribute to an increased risk of hypohydration and dehydration in the elderly.

With regard to physiology, the role of water in health is generally characterized in terms of deviations from an ideal hydrated state, generally in comparison to dehydration. The concept of dehydration encompasses both the process of losing body water and the state of dehydration. Much of the research on water and physical or mental functioning compares a euhydrated state, usually achieved by provision of water sufficient to overcome water loss, to a dehydrated state, which is achieved via withholding of fluids over time and during periods of heat stress or high activity. In general, provision of water is beneficial in individuals with a water deficit, but little research supports the notion that additional water in adequately hydrated individuals confers any benefit.

Physical performance

The role of water and hydration in physical activity, particularly in athletes and in the military, has been of considerable interest and is well-described in the scientific literature. 37 , – 39 During challenging athletic events, it is not uncommon for athletes to lose 6–10% of body weight through sweat, thus leading to dehydration if fluids have not been replenished. However, decrements in the physical performance of athletes have been observed under much lower levels of dehydration, i.e., as little as 2%. 38 Under relatively mild levels of dehydration, individuals engaging in rigorous physical activity will experience decrements in performance related to reduced endurance, increased fatigue, altered thermoregulatory capability, reduced motivation, and increased perceived effort. 40 , 41 Rehydration can reverse these deficits and reduce the oxidative stress induced by exercise and dehydration. 42 Hypohydration appears to have a more significant impact on high-intensity and endurance activity, such as tennis 43 and long-distance running, 44 than on anaerobic activities, 45 such as weight lifting, or on shorter-duration activities, such as rowing. 46

During exercise, individuals may not hydrate adequately when allowed to drink according to thirst. 32 After periods of physical exertion, voluntary fluid intake may be inadequate to offset fluid deficits. 1 Thus, mild-to-moderate dehydration can persist for some hours after the conclusion of physical activity. Research performed on athletes suggests that, principally at the beginning of the training season, they are at particular risk for dehydration due to lack of acclimatization to weather conditions or suddenly increased activity levels. 47 , 48 A number of studies show that performance in temperate and hot climates is affected to a greater degree than performance in cold temperatures. 41 , – 50 Exercise in hot conditions with inadequate fluid replacement is associated with hyperthermia, reduced stroke volume and cardiac output, decreases in blood pressure, and reduced blood flow to muscle. 51

During exercise, children may be at greater risk for voluntary dehydration. Children may not recognize the need to replace lost fluids, and both children as well as coaches need specific guidelines for fluid intake. 52 Additionally, children may require more time to acclimate to increases in environmental temperature than adults. 30 , 31 Recommendations are for child athletes or children in hot climates to begin athletic activities in a well-hydrated state and to drink fluids over and above the thirst threshold.

Cognitive performance

Water, or its lack (dehydration), can influence cognition. Mild levels of dehydration can produce disruptions in mood and cognitive functioning. This may be of special concern in the very young, very old, those in hot climates, and those engaging in vigorous exercise. Mild dehydration produces alterations in a number of important aspects of cognitive function such as concentration, alertness, and short-term memory in children (10–12 y), 32 young adults (18–25 y), 53 , – 56 and the oldest adults (50–82 y). 57 As with physical functioning, mild-to-moderate levels of dehydration can impair performance on tasks such as short-term memory, perceptual discrimination, arithmetic ability, visuomotor tracking, and psychomotor skills. 53 , – 56 However, mild dehydration does not appear to alter cognitive functioning in a consistent manner. 53 , – 58 In some cases, cognitive performance was not significantly affected in ranges from 2% to 2.6% dehydration. 56 , 58 Comparing across studies, performance on similar cognitive tests was divergent under dehydration conditions. 54 , 56 In studies conducted by Cian et al., 53 , 54 participants were dehydrated to approximately 2.8% either through heat exposure or treadmill exercise. In both studies, performance was impaired on tasks examining visual perception, short-term memory, and psychomotor ability. In a series of studies using exercise in conjunction with water restriction as a means of producing dehydration, D'Anci et al. 56 observed only mild decrements in cognitive performance in healthy young men and women athletes. In these experiments, the only consistent effect of mild dehydration was significant elevations of subjective mood score, including fatigue, confusion, anger, and vigor. Finally, in a study using water deprivation alone over a 24-h period, no significant decreases in cognitive performance were seen with 2.6% dehydration. 58 It is therefore possible that heat stress may play a critical role in the effects of dehydration on cognitive performance.

Reintroduction of fluids under conditions of mild dehydration can reasonably be expected to reverse dehydration-induced cognitive deficits. Few studies have examined how fluid reintroduction may alleviate the negative effects of dehydration on cognitive performance and mood. One study 59 examined how water ingestion affected arousal and cognitive performance in young people following a period of 12-h water restriction. While cognitive performance was not affected by either water restriction or water consumption, water ingestion affected self-reported arousal. Participants reported increased alertness as a function of water intake. Rogers et al. 60 observed a similar increase in alertness following water ingestion in both high- and low-thirst participants. Water ingestion, however, had opposite effects on cognitive performance as a function of thirst. High-thirst participants' performance on a cognitively demanding task improved following water ingestion, but low-thirst participants' performance declined. In summary, hydration status consistently affected self-reported alertness, but effects on cognition were less consistent.

Several recent studies have examined the utility of providing water to school children on attentiveness and cognitive functioning in children. 61 , – 63 In these experiments, children were not fluid restricted prior to cognitive testing, but were allowed to drink as usual. Children were then provided with a drink or no drink 20–45 min before the cognitive test sessions. In the absence of fluid restriction and without physiological measures of hydration status, the children in these studies should not be classified as dehydrated. Subjective measures of thirst were reduced in children given water, 62 and voluntary water intake in children varied from 57 mL to 250 mL. In these studies, as in the studies in adults, the findings were divergent and relatively modest. In the research led by Edmonds et al., 61 , 62 children in the groups given water showed improvements in visual attention. However, effects on visual memory were less consistent, with one study showing no effects of drinking water on a spot-the-difference task in 6–7-year-old children 61 and the other showing a significant improvement in a similar task in 7–9-year-old children. 62 In the research described by Benton and Burgess, 63 memory performance was improved by provision of water but sustained attention was not altered with provision of water in the same children.

Taken together, these studies indicate that low-to-moderate dehydration may alter cognitive performance. Rather than indicating that the effects of hydration or water ingestion on cognition are contradictory, many of the studies differ significantly in methodology and in measurement of cognitive behaviors. These variances in methodology underscore the importance of consistency when examining relatively subtle chances in overall cognitive performance. However, in those studies in which dehydration was induced, most combined heat and exercise; this makes it difficult to disentangle the effects of dehydration on cognitive performance in temperate conditions from the effects of heat and exercise. Additionally, relatively little is known about the mechanism of mild dehydration's effects on mental performance. It has been proposed that mild dehydration acts as a physiological stressor that competes with and draws attention from cognitive processes. 64 However, research on this hypothesis is limited and merits further exploration.

Dehydration and delirium

Dehydration is a risk factor for delirium and for delirium presenting as dementia in the elderly and in the very ill. 65 , – 67 Recent work shows that dehydration is one of several predisposing factors for confusion observed in long-term-care residents 67 ; however, in this study, daily water intake was used as a proxy measure for dehydration rather than other, more direct clinical assessments such as urine or plasma osmolality. Older people have been reported as having reduced thirst and hypodipsia relative to younger people. In addition, fluid intake and maintenance of water balance can be complicated by factors such as disease, dementia, incontinence, renal insufficiency, restricted mobility, and drug side effects. In response to primary dehydration, older people have less thirst sensation and reduced fluid intakes in comparison to younger people. However, in response to heat stress, while older people still display a reduced thirst threshold, they do ingest comparable amounts of fluid to younger people. 20

Gastrointestinal function

Fluids in the diet are generally absorbed in the proximal small intestine, and the absorption rate is determined by the rate of gastric emptying to the small intestine. Therefore, the total volume of fluid consumed will eventually be reflected in water balance, but the rate at which rehydration occurs is dependent upon factors affecting the rate of delivery of fluids to the intestinal mucosa. The gastric emptying rate is generally accelerated by the total volume consumed and slowed by higher energy density and osmolality. 68 In addition to water consumed in food (1 L/day) and beverages (circa 2–3 L/day), digestive secretions account for a far greater portion of water that passes through and is absorbed by the gastrointestinal tract (circa 8 L/day). 69 The majority of this water is absorbed by the small intestine, with a capacity of up to 15 L/day with the colon absorbing some 5 L/day. 69

Constipation, characterized by slow gastrointestinal transit, small, hard stools, and difficulty in passing stool, has a number of causes, including medication use, inadequate fiber intake, poor diet, and illness. 70 Inadequate fluid consumption is touted as a common culprit in constipation, and increasing fluid intake is a frequently recommended treatment. Evidence suggests, however, that increasing fluids is only useful to individuals in a hypohydrated state, and is of little utility in euhydrated individuals. 70 In young children with chronic constipation, increasing daily water intake by 50% did not affect constipation scores. 71 For Japanese women with low fiber intake, concomitant low water intake in the diet is associated with increased prevalence of constipation. 72 In older individuals, low fluid intake is a predictor for increased levels of acute constipation, 73 , 74 with those consuming the least amount of fluid having over twice the frequency of constipation episodes than those consuming the most fluid. In one trial, researchers compared the utility of carbonated mineral water in reducing functional dyspepsia and constipation scores to tap water in individuals with functional dyspepsia. 75 When comparing carbonated mineral water to tap water, participants reported improvements in subjective gastric symptoms, but there were no significant improvements in gastric or intestinal function. The authors indicate it is not possible to determine to what degree the mineral content of the two waters contributed to perceived symptom relief, as the mineral water contained greater levels of magnesium and calcium than the tap water. The available evidence suggests that increased fluid intake should only be indicated in individuals in a hypohydrated state. 69 , 71

Significant water loss can occur through the gastrointestinal tract, and this can be of great concern in the very young. In developing countries, diarrheal diseases are a leading cause of death in children, resulting in approximately 1.5–2.5 million deaths per year. 76 Diarrheal illness results not only in a reduction in body water, but also in potentially lethal electrolyte imbalances. Mortality in such cases can many times be prevented with appropriate oral rehydration therapy, by which simple dilute solutions of salt and sugar in water can replace fluid lost by diarrhea. Many consider application of oral rehydration therapy to be one of the significant public health developments of the last century. 77

Kidney function

As noted above, the kidney is crucial in regulating water balance and blood pressure as well as removing waste from the body. Water metabolism by the kidney can be classified into regulated and obligate. Water regulation is hormonally mediated, with the goal of maintaining a tight range of plasma osmolality (between 275 and 290 mOsm/kg). Increases in plasma osmolality and activation of osmoreceptors (intracellular) and baroreceptors (extracellular) stimulate hypothalamic release of arginine vasopressin (AVP). AVP acts at the kidney to decrease urine volume and promote retention of water, and the urine becomes hypertonic. With decreased plasma osmolality, vasopressin release is inhibited, and the kidney increases hypotonic urinary output.

In addition to regulating fluid balance, the kidneys require water for the filtration of waste from the bloodstream and excretion via urine. Water excretion via the kidney removes solutes from the blood, and a minimum obligate urine volume is required to remove the solute load with a maximum output volume of 1 L/h. 78 This obligate volume is not fixed, but is dependent upon the amount of metabolic solutes to be excreted and levels of AVP. Depending on the need for water conservation, basal urine osmolality ranges from 40 mOsm/kg to a maximum of 1,400 mOsm/kg. 78 The ability to both concentrate and dilute urine decreases with age, with a lower value of 92 mOsm/kg and an upper range falling between 500 and 700 mOsm/kg for individuals over the age of 70 years. 79 , – 81 Under typical conditions, in an average adult, urine volume of 1.5 to 2.0 L/day would be sufficient to clear a solute load of 900 to 1,200 mOsm/day. During water conservation and the presence of AVP, this obligate volume can decrease to 0.75–1.0 L/day and during maximal diuresis up to 20 L/day can be required to remove the same solute load. 78 , – 81 In cases of water loading, if the volume of water ingested cannot be compensated for with urine output, having overloaded the kidney's maximal output rate, an individual can enter a hyponatremic state.

Heart function and hemodynamic response

Blood volume, blood pressure, and heart rate are closely linked. Blood volume is normally tightly regulated by matching water intake and water output, as described in the section on kidney function. In healthy individuals, slight changes in heart rate and vasoconstriction act to balance the effect of normal fluctuations in blood volume on blood pressure. 82 Decreases in blood volume can occur, through blood loss (or blood donation), or loss of body water through sweat, as seen with exercise. Blood volume is distributed differently relative to the position of the heart, whether supine or upright, and moving from one position to the other can lead to increased heart rate, a fall in blood pressure, and, in some cases, syncope. This postural hypotension (or orthostatic hypotension) can be mediated by drinking 300–500 mL of water. 83 , 84 Water intake acutely reduces heart rate and increases blood pressure in both normotensive and hypertensive individuals. 85 These effects of water intake on the pressor effect and heart rate occur within 15–20 min of drinking water and can last for up to 60 min. Water ingestion is also beneficial in preventing vasovagal reaction with syncope in blood donors at high risk for post-donation syncope. 86 The effect of water intake in these situations is thought to be due to effects on the sympathetic nervous system rather than to changes in blood volume. 83 , 84 Interestingly, in rare cases, individuals may experience bradycardia and syncope after swallowing cold liquids. 87 , – 89 While swallow syncope can be seen with substances other than water, swallow syncope further supports the notion that the result of water ingestion in the pressor effect has both a neural component as well as a cardiac component.

Water deprivation and dehydration can lead to the development of headache. 90 Although this observation is largely unexplored in the medical literature, some observational studies indicate that water deprivation, in addition to impairing concentration and increasing irritability, can serve as a trigger for migraine and can also prolong migraine. 91 , 92 In those with water deprivation-induced headache, ingestion of water provided relief from headache in most individuals within 30 min to 3 h. 92 It is proposed that water deprivation-induced headache is the result of intracranial dehydration and total plasma volume. Although provision of water may be useful in relieving dehydration-related headache, the utility of increasing water intake for the prevention of headache is less well documented.

The folk wisdom that drinking water can stave off headaches has been relatively unchallenged, and has more traction in the popular press than in the medical literature. Recently, one study examined increased water intake and headache symptoms in headache patients. 93 In this randomized trial, patients with a history of different types of headache, including migraine and tension headache, were either assigned to a placebo condition (a nondrug tablet) or the increased water condition. In the water condition, participants were instructed to consume an additional volume of 1.5 L water/day on top of what they already consumed in foods and fluids. Water intake did not affect the number of headache episodes, but it was modestly associated with reduction in headache intensity and reduced duration of headache. The data from this study suggest that the utility of water as prophylaxis is limited in headache sufferers, and the ability of water to reduce or prevent headache in the broader population remains unknown.

One of the more pervasive myths regarding water intake is its relation to improvements of the skin or complexion. By improvement, it is generally understood that individuals are seeking to have a more “moisturized” look to the surface skin, or to minimize acne or other skin conditions. Numerous lay sources such as beauty and health magazines as well as postings on the Internet suggest that drinking 8–10 glasses of water a day will “flush toxins from the skin” and “give a glowing complexion” despite a general lack of evidence 94 , 95 to support these proposals. The skin, however, is important for maintaining body water levels and preventing water loss into the environment.

The skin contains approximately 30% water, which contributes to plumpness, elasticity, and resiliency. The overlapping cellular structure of the stratum corneum and lipid content of the skin serves as “waterproofing” for the body. 96 Loss of water through sweat is not indiscriminate across the total surface of the skin, but is carried out by eccrine sweat glands, which are evenly distributed over most of the body surface. 97 Skin dryness is usually associated with exposure to dry air, prolonged contact with hot water and scrubbing with soap (both strip oils from the skin), medical conditions, and medications. While more serious levels of dehydration can be reflected in reduced skin turgor, 98 , 99 with tenting of the skin acting as a flag for dehydration, overt skin turgor in individuals with adequate hydration is not altered. Water intake, particularly in individuals with low initial water intake, can improve skin thickness and density as measured by sonogram, 100 offsets transepidermal water loss, and can improve skin hydration. 101 Adequate skin hydration, however, is not sufficient to prevent wrinkles or other signs of aging, which are related to genetics and to sun and environmental damage. Of more utility to individuals already consuming adequate fluids is the use of topical emollients; these will improve skin barrier function and improve the look and feel of dry skin. 102 , 103

Many chronic diseases have multifactorial origins. In particular, differences in lifestyle and the impact of environment are known to be involved and constitute risk factors that are still being evaluated. Water is quantitatively the most important nutrient. In the past, scientific interest with regard to water metabolism was mainly directed toward the extremes of severe dehydration and water intoxication. There is evidence, however, that mild dehydration may also account for some morbidities. 4 , 104 There is currently no consensus on a “gold standard” for hydration markers, particularly for mild dehydration. As a consequence, the effects of mild dehydration on the development of several disorders and diseases have not been well documented.

There is strong evidence showing that good hydration reduces the risk of urolithiasis (see Table 2 for evidence categories). Less strong evidence links good hydration with reduced incidence of constipation, exercise asthma, hypertonic dehydration in the infant, and hyperglycemia in diabetic ketoacidosis. Good hydration is associated with a reduction in urinary tract infections, hypertension, fatal coronary heart disease, venous thromboembolism, and cerebral infarct, but all these effects need to be confirmed by clinical trials. For other conditions such as bladder or colon cancer, evidence of a preventive effect of maintaining good hydration is not consistent (see Table 3 ).

Categories of evidence used in evaluating the quality of reports.

Data adapted from Manz. 104

Summary of evidence for association of hydration status with chronic diseases.

Categories of evidence: described in Table 2 .

Water consumption, water requirements, and energy intake are linked in fairly complex ways. This is partially because physical activity and energy expenditures affect the need for water but also because a large shift in beverage consumption over the past century or more has led to consumption of a significant proportion of our energy intake from caloric beverages. Nonregulatory beverage intake, as noted earlier, has assumed a much greater role for individuals. 19 This section reviews current patterns of water intake and then refers to a full meta-analysis of the effects of added water on energy intake. This includes adding water to the diet and water replacement for a range of caloric and diet beverages, including sugar-sweetened beverages, juice, milk, and diet beverages. The third component is a discussion of water requirements and suggestions for considering the use of mL water/kcal energy intake as a metric.

Patterns and trends of water consumption

Measurement of total fluid water consumption in free-living individuals is fairly new in focus. As a result, the state of the science is poorly developed, data are most likely fairly incomplete, and adequate validation of the measurement techniques used is not available. Presented here are varying patterns and trends of water intake for the United States over the past three decades followed by a brief review of the work on water intake in Europe.

There is really no existing information to support an assumption that consumption of water alone or beverages containing water affects hydration differentially. 3 , 105 Some epidemiological data suggest water might have different metabolic effects when consumed alone rather than as a component of caffeinated or flavored or sweetened beverages; however, these data are at best suggestive of an issue deserving further exploration. 106 , 107 As shown below, the research of Ershow et al. indicates that beverages not consisting solely of water do contain less than 100% water.

One study in the United States has attempted to examine all the dietary sources of water. 16 , 17 These data are cited in Table 4 as the Ershow study and were based on National Food Consumption Survey food and fluid intake data from 1977–1978. These data are presented in Table 4 for children aged 2–18 years (Panel A) and for adults aged 19 years and older (Panel B). Ershow et al. 16 , 17 spent a great deal of time working out ways to convert USDA dietary data into water intake, including water absorbed during the cooking process, water in food, and all sources of drinking water.

Beverage pattern trends in the United States for children aged 2–18 years and adults aged 19 years and older, (nationally representative).

Note: The data are age and sex adjusted to 1965.

Values stem from the Ershow calculations. 16

These researchers created a number of categories and used a range of factors measured in other studies to estimate the water categories. The water that is found in food, based on food composition table data, was 393 mL for children. The water that was added as a result of cooking (e.g., rice) was 95 mL. Water consumed as a beverage directly as water was 624 mL. The water found in other fluids, as noted, comprised the remainder of the milliliters, with the highest levels in whole-fat milk and juices (506 mL). There is a small discrepancy between the Ershow data regarding total fluid intake measures for these children and the normal USDA figures. That is because the USDA does not remove milk fats and solids, fiber, and other food constituents found in beverages, particularly juice and milk.

A key point illustrated by these nationally representative US data is the enormous variability between survey waves in the amount of water consumed (see Figure 1 , which highlights the large variation in water intake as measured in these surveys). Although water intake by adults and children increased and decreased at the same time, for reasons that cannot be explained, the variation was greater among children than adults. This is partly because the questions the surveys posed varied over time and there was no detailed probing for water intake, because the focus was on obtaining measures of macro- and micronutrients. Dietary survey methods used in the past have focused on obtaining data on foods and beverages containing nutrient and non-nutritive sweeteners but not on water. Related to this are the huge differences between the the USDA surveys and the National Health and Nutrition Examination Survey (NHANES) performed in 1988–1994 and in 1999 and later. In addition, even the NHANES 1999–2002 and 2003–2006 surveys differ greatly. These differences reflect a shift in the mode of questioning with questions on water intake being included as part of a standard 24-h recall rather than as stand-alone questions. Water intake was not even measured in 1965, and a review of the questionnaires and the data reveals clear differences in the way the questions have been asked and the limitations on probes regarding water intake. Essentially, in the past people were asked how much water they consumed in a day and now they are asked for this information as part of a 24-h recall survey. However, unlike for other caloric and diet beverages, there are limited probes for water alone. The results must thus be viewed as crude approximations of total water intake without any strong research to show if they are over- or underestimated. From several studies of water and two ongoing randomized controlled trials performed by us, it is clear that probes that include consideration of all beverages and include water as a separate item result in the provision of more complete data.

Water consumption trends from USDA and NHANES surveys (mL/day/capita), nationally representative. Note: this includes water from fluids only, excluding water in foods. Sources for 1965, 1977–1978, 1989–1991, and 1994–1998, are USDA. Others are NHANES and 2005–2006 is joint USDA and NHANES.

Water consumption data for Europe are collected far more selectively than even the crude water intake questions from NHANES. A recent report from the European Food Safety Agency provides measures of water consumption from a range of studies in Europe. 4 , – 109 Essentially, what these studies show is that total water intake is lower across Europe than in the United States. As with the US data, none are based on long-term, carefully measured or even repeated 24-h recall measures of water intake from food and beverages. In an unpublished examination of water intake in UK adults in 1986–1987 and in 2001–2002, Popkin and Jebb have found that although intake increased by 226 mL/day over this time period, it was still only 1,787 mL/day in the latter period (unpublished data available from BP); this level is far below the 2,793 mL/day recorded in the United States for 2005–2006 or the earlier US figures for comparably aged adults.

A few studies have been performed in the United States and Europe utilizing 24-h urine and serum osmolality measures to determine total water turnover and hydration status. Results of these studies suggest that US adults consume over 2,100 mL of water per day while adults in Europe consume less than half a liter. 4 , 110 Data on total urine collection would appear to be another useful measure for examining total water intake. Of course, few studies aside from the Donald Study of an adolescent cohort in Germany have collected such data on population levels for large samples. 109

Effects of water consumption on overall energy intake

There is an extensive body of literature that focuses on the impact of sugar-sweetened beverages on weight and the risk of obesity, diabetes, and heart disease; however, the perspective of providing more water and its impact on health has not been examined. The literature on water does not address portion sizes; instead, it focuses mainly on water ad libitum or in selected portions compared with other caloric beverages. A detailed meta-analysis of the effects of water intake alone (i.e., adding additional water) and as a replacement for sugar-sweetened beverages, juice, milk, and diet beverages appears elsewhere. 111

In general, the results of this review suggest that water, when consumed in place of sugar-sweetened beverages, juice, and milk, is linked with reduced energy intake. This finding is mainly derived from clinical feeding studies but also from one very good randomized, controlled school intervention and several other epidemiological and intervention studies. Aside from the issue of portion size, factors such as the timing of beverage and meal intake (i.e., the delay between consumption of the beverage and consumption of the meal) and types of caloric sweeteners remain to be considered. However, when beverages are consumed in normal free-living conditions in which five to eight daily eating occasions are the norm, the delay between beverage and meal consumption may matter less. 112 , – 114

The literature on the water intake of children is extremely limited. However, the excellent German school intervention with water suggests the effects of water on the overall energy intake of children might be comparable to that of adults. 115 In this German study, children were educated on the value of water and provided with special filtered drinking fountains and water bottles in school. The intervention schoolchildren increased their water intake by 1.1 glasses/day ( P  < 0.001) and reduced their risk of overweight by 31% (OR = 0.69, P  = 0.40).

Classically, water data are examined in terms of milliliters (or some other measure of water volume consumed per capita per day by age group). This measure does not link fluid intake and caloric intake. Disassociation of fluid and calorie intake is difficult for clinicians dealing with older persons with reduced caloric intake. This milliliter water measure assumes some mean body size (or surface area) and a mean level of physical activity – both of which are determinants of not only energy expenditure but also water balance. Children are dependent on adults for access to water, and studies suggest that their larger surface area to volume ratio makes them susceptible to changes in skin temperatures linked with ambient temperature shifts. 116 One option utilized by some scholars is to explore food and beverage intake in milliliters per kilocalorie (mL/kcal), as was done in the 1989 US recommended dietary allowances. 4 , 117 This is an option that is interpretable for clinicians and which incorporates, in some sense, body size or surface area and activity. Its disadvantage is that water consumed with caloric beverages affects both the numerator and the denominator; however, an alternative measure that could be independent of this direct effect on body weight and/or total caloric intake is not presently known.

Despite its critical importance in health and nutrition, the array of available research that serves as a basis for determining requirements for water or fluid intake, or even rational recommendations for populations, is limited in comparison with most other nutrients. While this deficit may be partly explained by the highly sensitive set of neurophysiological adaptations and adjustments that occur over a large range of fluid intakes to protect body hydration and osmolarity, this deficit remains a challenge for the nutrition and public health community. The latest official effort at recommending water intake for different subpopulations occurred as part of the efforts to establish Dietary Reference Intakes in 2005, as reported by the Institute of Medicine of the National Academies of Science. 3 As a graphic acknowledgment of the limited database upon which to express estimated average requirements for water for different population groups, the Committee and the Institute of Medicine stated: “While it might appear useful to estimate an average requirement (an EAR) for water, an EAR based on data is not possible.” Given the extreme variability in water needs that are not solely based on differences in metabolism, but also on environmental conditions and activities, there is not a single level of water intake that would assure adequate hydration and optimum health for half of all apparently healthy persons in all environmental conditions. Thus, an adequate intake (AI) level was established in place of an EAR for water.

The AIs for different population groups were set as the median water intakes for populations, as reported in the National Health and Nutrition Examination Surveys; however, the intake levels reported in these surveys varied greatly based on the survey years (e.g., NHANES 1988–1994 versus NHANES 1999–2002) and were also much higher than those found in the USDA surveys (e.g., 1989–1991, 1994–1998, or 2005–2006). If the AI for adults, as expressed in Table 5 , is taken as a recommended intake, the wisdom of converting an AI into a recommended water or fluid intake seems questionable. The first problem is the almost certain inaccuracy of the fluid intake information from the national surveys, even though that problem may also exist for other nutrients. More importantly, from the standpoint of translating an AI into a recommended fluid intake for individuals or populations, is the decision that was made when setting the AI to add an additional roughly 20% of water intake, which is derived from some foods in addition to water and beverages. While this may have been a legitimate effort to use total water intake as a basis for setting the AI, the recommendations that derive from the IOM report would be better directed at recommendations for water and other fluid intake on the assumption that the water content of foods would be a “passive” addition to total water intake. In this case, the observations of the dietary reference intake committee that it is necessary for water intake to meet needs imposed by metabolism and environmental conditions must be extended to consider three added factors, namely body size, gender, and physical activity. Those are the well-studied factors that allow a rather precise measurement and determination of energy intake requirements. It is, therefore, logical that those same factors might underlie recommendations to meet water intake needs in the same populations and individuals. Consideration should also be given to the possibility that water intake needs would best be expressed relative to the calorie requirements, as is done regularly in the clinical setting, and data should be gathered to this end through experimental and population research.

Water requirements expressed in relation to energy recommendations.

AI for total fluids derived from dietary reference intakes for water, potassium, sodium, chloride, and sulphate.

Ratios for water intake based on the AI for water in liters/day calculated using EER for each range of physical activity. EER adapted from the Institute of Medicine Dietary Reference Intakes Macronutrients Report, 2002.

It is important to note that only a few countries include water on their list of nutrients. 118 The European Food Safety Authority is developing a standard for all of Europe. 105 At present, only the United States and Germany provide AI values for water. 3 , 119

Another approach to the estimation of water requirements, beyond the limited usefulness of the AI or estimated mean intake, is to express water intake requirements in relation to energy requirements in mL/kcal. An argument for this approach includes the observation that energy requirements for each age and gender group are strongly evidence-based and supported by extensive research taking into account both body size and activity level, which are crucial determinants of energy expenditure that must be met by dietary energy intake. Such measures of expenditure have used highly accurate methods, such as doubly labeled water; thus, estimated energy requirements have been set based on solid data rather than the compromise inherent in the AIs for water. Those same determinants of energy expenditure and recommended intake are also applicable to water utilization and balance, and this provides an argument for pegging water/fluid intake recommendations to the better-studied energy recommendations. The extent to which water intake and requirements are determined by energy intake and expenditure is understudied, but in the clinical setting it has long been practice to supply 1 mL/kcal administered by tube to patients who are unable to take in food or fluids. Factors such as fever or other drivers of increased metabolism affect both energy expenditure and fluid loss and are thus linked in clinical practice. This concept may well deserve consideration in the setting of population intake goals.

Finally, for decades there has been discussion about expressing nutrient requirements per 1,000 kcal so that a single number would apply reasonably across the spectrum of age groups. This idea, which has never been adopted by the Institute of Medicine and the National Academies of Science, may lend itself to an improved expression of water/fluid intake requirements, which must eventually replace the AIs. Table 5 presents the IOM water requirements and then develops a ratio of mL/kcal based on them. The European Food Safety Agency refers positively to the possibility of expressing water intake recommendations in mL/kcal as a function of energy requirements. 105 Outliers in the adult male categories, which reach ratios as high as 1.5, may well be based on the AI data from the United States, which are above those in the more moderate and likely more accurate European recommendations.

The topic of utilizing mL/kcal to examine water intake and water gaps is explored in Table 6 , which takes the full set of water intake AIs for each age-gender grouping and examines total intake. The data suggest a high level of fluid deficiency. Since a large proportion of fluids in the United States is based on caloric beverages and this proportion has changed markedly over the past 30 years, fluid intake increases both the numerator and the denominator of this mL/kcal relationship. Nevertheless, even using 1 mL/kcal as the AI would leave a gap for all children and adolescents. The NHANES physical activity data were also translated into METS/day to categorize all individuals by physical activity level and thus varying caloric requirements. Use of these measures reveals a fairly large fluid gap, particularly for adult males as well as children ( Table 6 ).

Water intake and water intake gaps based on US Water Adequate Intake Recommendations (based on utilization of water and physical activity data from NHANES 2005–2006).

Note: Recommended water intake for actual activity level is the upper end of the range for moderate and active.

A weighted average for the proportion of individuals in each METS-based activity level.

This review has pointed out a number of issues related to water, hydration, and health. Since water is undoubtedly the most important nutrient and the only one for which an absence will prove lethal within days, understanding of water measurement and water requirements is very important. The effects of water on daily performance and short- and long-term health are quite clear. The existing literature indicates there are few negative effects of water intake while the evidence for positive effects is quite clear.

Little work has been done to measure total fluid intake systematically, and there is no understanding of measurement error and best methods of understanding fluid intake. The most definitive US and European documents on total water requirements are based on these extant intake data. 3 , 105 The absence of validation methods for water consumption intake levels and patterns represents a major gap in knowledge. Even varying the methods of probing in order to collect better water recall data has been little explored.

On the other side of the issue is the need to understand total hydration status. There are presently no acceptable biomarkers of hydration status at the population level, and controversy exists about the current knowledge of hydration status among older Americans. 6 , 120 Thus, while scholars are certainly focused on attempting to create biomarkers for measuring hydration status at the population level, the topic is currently understudied.

As noted, the importance of understanding the role of fluid intake on health has emerged as a topic of increasing interest, partially because of the trend toward rising proportions of fluids being consumed in the form of caloric beverages. The clinical, epidemiological, and intervention literature on the effects of added water on health are covered in a related systematic review. 111 The use of water as a replacement for sugar-sweetened beverages, juice, or whole milk has clear effects in that energy intake is reduced by about 10–13% of total energy intake. However, only a few longer-term systematic interventions have investigated this topic and no randomized, controlled, longer-term trials have been published to date. There is thus very minimal evidence on the effects of just adding water to the diet and of replacing water with diet beverages.

There are many limitations to this review. One certainly is the lack of discussion of potential differences in the metabolic functioning of different types of beverages. 121 Since the literature in this area is sparse, however, there is little basis for delving into it at this point. A discussion of the potential effects of fructose (from all caloric sweeteners when consumed in caloric beverages) on abdominal fat and all of the metabolic conditions directly linked with it (e.g., diabetes) is likewise lacking. 122 , – 125 A further limitation is the lack of detailed review of the array of biomarkers being considered to measure hydration status. Since there is no measurement in the field today that covers more than a very short time period, except for 24-hour total urine collection, such a discussion seems premature.

Some ways to examine water requirements have been suggested in this review as a means to encourage more dialogue on this important topic. Given the significance of water to our health and of caloric beverages to our total energy intake, as well as the potential risks of nutrition-related noncommunicable diseases, understanding both the requirements for water in relation to energy requirements, and the differential effects of water versus other caloric beverages, remain important outstanding issues.

This review has attempted to provide some sense of the importance of water to our health, its role in relationship to the rapidly increasing rates of obesity and other related diseases, and the gaps in present understanding of hydration measurement and requirements. Water is essential to our survival. By highlighting its critical role, it is hoped that the focus on water in human health will sharpen.

The authors wish to thank Ms. Frances L. Dancy for administrative assistance, Mr. Tom Swasey for graphics support, Dr. Melissa Daniels for assistance, and Florence Constant (Nestle's Water Research) for advice and references.

This work was supported by the Nestlé Waters, Issy-les-Moulineaux, France, 5ROI AGI0436 from the National Institute on Aging Physical Frailty Program, and NIH R01-CA109831 and R01-CA121152.

Declaration of interest

The authors have no relevant interests to declare.

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Valtin H . “Drink at least eight glasses of water a day.” Really? Is there scientific evidence for “8 x 8”? Am J Physiol Regul Integr Comp Physiol. 2002 ; 283 : R993 – 1004 .

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Sichert-Hellert W Kersting M Manz F . Fifteen year trends in water intake in German children and adolescents: results of the DONALD Study. Dortmund Nutritional and Anthropometric Longitudinally Designed Study . Acta Paediatr. 2001 ; 90 : 732 – 737 .

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Popkin BM Duffey KJ. Does hunger and satiety drive eating anymore? Increasing eating occasions and decreasing time between eating occasions in the United States . Am J Clin Nutr . 2010 ; 91 : 1342 – 1347 .

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Stookey JD Pieper CF Cohen HJ . Is the prevalence of dehydration among community-dwelling older adults really low? Informing current debate over the fluid recommendation for adults aged 70+years . Public Health Nutr. 2005 ; 8 : 1275 – 1285 .

Malik VS Popkin BM Bray G Després J-P Hu FB. Sugar sweetened beverages, obesity, type 2 diabetes and cardiovascular disease risk . Circulation 2010 ; 121 : 1356 – 1364 .

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Stanhope KL . Consuming fructose-sweetened, not glucose-sweetened, beverages increases visceral adiposity and lipids and decreases insulin sensitivity in overweight/obese humans . J Clin Investigat. 2009 ; 119 : 1322 – 1334 .

Stanhope KL Havel PJ . Endocrine and metabolic effects of consuming beverages sweetened with fructose, glucose, sucrose, or high-fructose corn syrup . Am J Clin Nutr. 2008 ; 88 (Suppl): S1733 – S1737 .

Stanhope KL Griffen SC Bair BR Swarbrick MM Keim NL Havel PJ . Twenty-four-hour endocrine and metabolic profiles following consumption of high-fructose corn syrup-, sucrose-, fructose-, and glucose-sweetened beverages with meals . Am J Clin Nutr. 2008 ; 87 : 1194 – 1203 .

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Burge MR Garcia N Qualls CR Schade DS . Differential effects of fasting and dehydration in the pathogenesis of diabetic ketoacidosis . Metabolism. 2001 ; 50 : 171 – 177 .

Jayashree M Singhi S . Diabetic ketoacidosis: predictors of outcome in a pediatric intensive care unit of a developing country . Pediatr Crit Care Med. 2004 ; 5 : 427 – 433 .

Hebert LA Greene T Levey A Falkenhain ME Klahr S . High urine volume and low urine osmolality are risk factors for faster progression of renal disease . Am J Kidney Dis. 2003 ; 41 : 962 – 971 .

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Blanker MH Bernsen RM Ruud Bosch JL , et al . Normal values and determinants of circadian urine production in older men: a population based study . J Urol. 2002 ; 168 : 1453 – 1457 .

Chan J Knutsen SF Blix GG Lee JW Fraser GE . Water, other fluids, and fatal coronary heart disease: the Adventist Health Study . Am J Epidemiol. 2002 ; 155 : 827 – 833 .

Kelly J Hunt BJ Lewis RR , et al . Dehydration and venous thromboembolism after acute stroke . QJM. 2004 ; 97 : 293 – 296 .

Bhalla A Sankaralingam S Dundas R Swaminathan R Wolfe CD Rudd AG . Influence of raised plasma osmolality on clinical outcome after acute stroke . Stroke. 2000 ; 31 : 2043 – 2048 .

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• dehydration
• energy intake
• water drinking
• fluid intake
• water requirements

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Carlsbad Desalination

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Nitrogen and Phosphorus Removal

Combining nitrite-shunt/anammox with side-stream processes

• 01 Climate Change
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• 04 Biological Nutrient Removal

Topics of Focus

In the United States alone, billions of gallons of water are treated each day at water resource recovery facilities. Once the water is clean, a different challenge remains: determining what to do with the solids that are removed during the treatment process. The resulting mixture is often a unique semi-solid blend of organic and inorganic materials, trace elements, chemicals, and even pathogens, so there is no across the board solution for handling and processing the combinations of constituents that may be present.

Because these solids are often rich in nutrients, like nitrogen and phosphorus—which also happen to be the perfect ingredients for promoting healthy soil and plant growth—many facilities have turned to land application. Before these solids can be put to use for things like fertilizing farmland, however, they must undergo rigorous treatment to meet stringent regulations, at which point they become known as biosolids.

For more information, contact Ashwin Dhanasekar .

Characterization and Contamination Testing of Source Separated Organic Feedstocks and Slurries for Co-Digestion at Resource Recovery Facilities

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A key challenge with source separated organic (SSO) feedstock co-substrate is that its composition, quality, and characteristics differ between geographical locations and can change over time. This causes challenges and uncertainties for pre-treaters, substrate brokers, facilities accepting this material, operators...

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(Denver, CO) 9/12/23 - The Water Research Foundation (WRF) is now accepting proposals for 22 research projects totaling $4.9M that will advance the science of water for communities around the...

Climate Change

Climate change is altering our natural hydrologic cycle, creating uncertainty when it comes to the quality and quantity of water sources. WRF’s research on climate change covers the key areas of climate risk assessment, climate adaptation, and mitigation strategies.

Because the first step in preparing for climate change is understanding the potential and variable impacts these changes can have on water sources and treatment systems, WRF research tracks potential outcomes, considering a variety of possibilities, and provides resources and tools to help facilities identify and address risks and vulnerabilities in their operations and infrastructure.

Implementing climate change adaptation strategies will be critical as the water sector moves forward. WRF’s research in this area helps utilities create better long- and short-term adaptation plans, respond more effectively to severe weather, and improve infrastructure and operations to meet changing needs, including the production of onsite energy systems and reliable back-up power to protect critical services.

The water sector must also have a hand in mitigating the root causes of climate change. By pioneering approaches to improve energy efficiency, including process optimization, improved energy management, and the use of renewable energy, WRF is helping the water sector decrease activity that is driving these changes.

For more information, contact Harry Zhang .

Holistic Approaches to Flood Mitigation Planning and Modeling under Extreme Events and Climate Impacts

Municipalities and utilities are facing unprecedented challenges in planning for extreme precipitation and flooding events, which are occurring more frequently and unpredictably. A holistic approach to flood mitigation planning and modeling, including partnerships between stakeholders, is needed to balance competing...

One Water Cities: A Self-Assessment Framework

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Cyanobacteria & Cyanotoxins

Aquatic microscopic algae and cyanobacteria (formerly known as blue-green algae) occur naturally in most surface waters. However certain nutrient and temperature conditions can cause them to multiply rapidly, leading to “blooms.” Under certain conditions, some species of cyanobacteria can produce toxic secondary metabolites or cyanotoxins, which may pose health risks to humans and animals. Even when cyanobacteria are not toxic, they can produce unpleasant tastes and odors.

Cyanobacteria continue to be among the most problematic organisms in fresh water systems. Without clear guidance or consensus regulations in place, many utilities struggle with responding to cyanobacterial harmful algal bloom (cHAB) events. Since 1994, WRF has completed more than 40 research projects on these microscopic organisms and the cyanotoxins they produce, helping facilities detect, monitor, and manage these organisms—as well as communicate with the public.

For more information, contact Sydney Samples .

Refinement and Standardization of Cyanotoxin Analytical Techniques for Drinking Water

There is uncertainty relating to the screening and confirmation of cyanotoxin samples. Water utilities need robust and dependable methods to monitor cyanotoxins in source water, through the treatment process, and at the tap, as well as to make appropriate decisions...

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PFAS Communication Guidance

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Per- and Polyfluoroalkyl Substances

Per- and polyfluoroalkyl substances (PFAS) are man-made compounds with fluorinated carbon chains. They are resistant to heat, oil, and water, making them useful in a wide variety of products, including...

Disinfection Byproducts (DBPs)

The use of strong oxidants to disinfect water has virtually eliminated waterborne diseases like typhoid, cholera, and dysentery in developed countries. However, research has shown that chlorine interacts with natural organic matter present in water supplies to form regulated and emerging disinfection byproducts (DBPs).

To minimize the formation of regulated DBPs and comply with existing regulations, water utilities have increasingly been moving away from chlorine to use alternative disinfectants like chloramine, or installing more advanced and costly treatment processes, such as ozone or granular activated carbon to remove DBP precursors. However, while reducing the formation of halogenated DBPs, alternative oxidants have been shown to favor the formation of other DBPs (e.g., ozone producing bromate and halonitromethanes, and chloramines producing N-nitrosodimethylamine and iodinated DBPs). 

For more information, contact Kenan Ozekin .

Impact of Haloacetic Acid MCL Revisions on DBP Exposure and Health Risk Reduction

The U.S. Environmental Protection Agency (EPA) is considering changes to the disinfectant and disinfection byproducts (D/DBP) rule. Specifically, there may be a shift from the currently regulated five haloacetic acids (HAA5) to nine (HAA9), which would include four additional brominated...

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Energy Optimization

For most water facilities, energy is one of the highest costs in their operating budget. Stricter regulations are pushing facilities to use even more advanced—and energy-intensive—treatment technologies. Optimizing energy use can provide huge cost savings and numerous additional benefits, including improving air quality, protecting the environment, and bolstering energy security. WRF has published more than 100 projects that explore ways to not only optimize current energy use, but to generate power as well—setting the course for a self-sufficient water sector.

Developing a Framework for Quantifying Energy Optimization Reporting

Energy projects within the water sector are often discretionary and initiated based on projected annual energy savings metrics. The water sector lacks standard energy savings estimation procedures, as well as measurement and verification approaches and procedures that adhere to the...

Interview with Dr. Amy Pruden

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Intelligent Water Systems

As with other industries, newly developed technologies drive water utilities to adapt their day-to-day operations. Water networks have been a special focus, with new instrumentation options for water production, transmission, distribution, wastewater collection, and consumer end-points coming to market. Implementing these technologies can improve the efficiency and reliability of water networks, but with myriad options, utilities need guidance on which technologies are most worthwhile and how they should be implemented. 

Quantifying the Impact of Artificial Intelligence/Machine Learning-Based Approaches to Utility Performance

The purpose of this project is to survey the water industry and identify the use cases for artificial intelligence (AI) and machine learning (ML), quantify their benefits, and provide a framework for others to be able to make the same...

2024 Intelligent Water Systems Challenge

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The Water Research Foundation and Water Environment Federation Launch the Fifth Intelligent Water Systems Challenge

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Microbes & Pathogens

Control of microbes in water systems is critical to achieving water quality and public health goals. While most microbes are not considered human pathogens, certain microbes can pose health risks or contribute undesirable tastes and odors. 

Since the early 20th century, modern drinking water treatment has made great advancements in the detection, removal, and inactivation of bacteria, viruses, and protozoa. As technologies in the drinking water space continue to progress, new challenges have arisen in the form of opportunistic premise plumbing pathogens. 

Wastewater and stormwater utilities also play an essential role in reducing the pathogen load to receiving waters used for recreation.  Additionally, more recent advancements in water reuse, especially direct potable reuse, demand more understanding of pathogen detection, removal, and inactivation in wastewater. 

For more information, contact Grace Jang (drinking water & reuse) or Lola Olabode (wastewater).

Demonstrating the Effectiveness of Flushing for Reducing the Levels of Legionella in Service Lines and Premise Plumbing

Legionella are pervasive environmental bacteria that can incidentally cause severe and sometimes fatal infections upon inhalation. Because legionella inhabit engineered environments and proliferate in warm, stagnant premise water systems, the majority of outbreaks are associated with preventable water system maintenance...

Interview with Cheryl Norton

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Resource Recovery

In recent decades, the wastewater sector has moved away from the idea of wastewater treatment plants as waste disposal facilities, instead envisioning these plants as water resource recovery facilities (WRRFs). WRRFs can produce clean water, recover nutrients (such as phosphorus and nitrogen), and potentially reduce fossil fuel consumption through the production and use of renewable energy.

For more information, contact Jeff Moeller .

Recent Updates

Reporting Period: January 1 – April 15, 2024

Reporting Period: November 2023 – April 30, 2024

Reporting Period: August 1, 2023 – March 15, 2024

Reporting Period: September 15, 2023 – March 20, 2024

Reporting Period: October 1, 2023 – December 31, 2023

Reporting Period: December 7, 2023 – March 6, 2024

Reporting Period: October 1, 2023 – April 1, 2024

Reporting Period: January 1 – March 31, 2024

Reporting Period: December 1, 2023 – March 1, 2024

Throughout the year, WRF hosts and participates in events that focus on critical water quality issues. From web seminars to research workshops, these events provide opportunities for you to learn about new research from water quality experts and to share ideas and connect with other industry professionals.

Guidance for Using Pipe Rigs to Inform Lead and Copper Corrosion Control Treatment Decisions

Guidance for Complying with the Lead and Copper Rule Revisions for Water Systems with No- to Low Prevalence of Lead Service Lines (LSL, LSLs)

Advances in water research.

This issue highlights the essential research The Water Research Foundation delivered in 2023 thanks to the valuable contributions of our researchers, participating utilities, and countless volunteers.

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• Nutrition and healthy eating

Water: How much should you drink every day?

Water is essential to good health. Are you getting enough? These guidelines can help you find out.

How much water should you drink each day? It's a simple question with no easy answer.

Studies have produced varying recommendations over the years. But your individual water needs depend on many factors, including your health, how active you are and where you live.

No single formula fits everyone. But knowing more about your body's need for fluids will help you estimate how much water to drink each day.

What are the health benefits of water?

Water is your body's principal chemical component and makes up about 50% to 70% of your body weight. Your body depends on water to survive.

Every cell, tissue and organ in your body needs water to work properly. For example, water:

• Gets rid of wastes through urination, perspiration and bowel movements
• Keeps your temperature normal
• Lubricates and cushions joints
• Protects sensitive tissues

Lack of water can lead to dehydration — a condition that occurs when you don't have enough water in your body to carry out normal functions. Even mild dehydration can drain your energy and make you tired.

How much water do you need?

Every day you lose water through your breath, perspiration, urine and bowel movements. For your body to function properly, you must replenish its water supply by consuming beverages and foods that contain water.

So how much fluid does the average, healthy adult living in a temperate climate need? The U.S. National Academies of Sciences, Engineering, and Medicine determined that an adequate daily fluid intake is:

• About 15.5 cups (3.7 liters) of fluids a day for men
• About 11.5 cups (2.7 liters) of fluids a day for women

These recommendations cover fluids from water, other beverages and food. About 20% of daily fluid intake usually comes from food and the rest from drinks.

What about the advice to drink 8 glasses a day?

You've probably heard the advice to drink eight glasses of water a day. That's easy to remember, and it's a reasonable goal.

Most healthy people can stay hydrated by drinking water and other fluids whenever they feel thirsty. For some people, fewer than eight glasses a day might be enough. But other people might need more.

You might need to modify your total fluid intake based on several factors:

• Exercise. If you do any activity that makes you sweat, you need to drink extra water to cover the fluid loss. It's important to drink water before, during and after a workout.
• Environment. Hot or humid weather can make you sweat and requires additional fluid. Dehydration also can occur at high altitudes.
• Overall health. Your body loses fluids when you have a fever, vomiting or diarrhea. Drink more water or follow a doctor's recommendation to drink oral rehydration solutions. Other conditions that might require increased fluid intake include bladder infections and urinary tract stones.
• Pregnancy and breast-feeding. If you are pregnant or breast-feeding, you may need additional fluids to stay hydrated.

Is water the only option for staying hydrated?

No. You don't need to rely only on water to meet your fluid needs. What you eat also provides a significant portion. For example, many fruits and vegetables, such as watermelon and spinach, are almost 100% water by weight.

In addition, beverages such as milk, juice and herbal teas are composed mostly of water. Even caffeinated drinks — such as coffee and soda — can contribute to your daily water intake. But go easy on sugar-sweetened drinks. Regular soda, energy or sports drinks, and other sweet drinks usually contain a lot of added sugar, which may provide more calories than needed.

How do I know if I'm drinking enough?

Your fluid intake is probably adequate if:

• You rarely feel thirsty
• Your urine is colorless or light yellow

Your doctor or dietitian can help you determine the amount of water that's right for you every day.

To prevent dehydration and make sure your body has the fluids it needs, make water your beverage of choice. It's a good idea to drink a glass of water:

• With each meal and between meals
• Before, during and after exercise
• If you feel thirsty

Should I worry about drinking too much water

Drinking too much water is rarely a problem for healthy, well-nourished adults. Athletes occasionally may drink too much water in an attempt to prevent dehydration during long or intense exercise. When you drink too much water, your kidneys can't get rid of the excess water. The sodium content of your blood becomes diluted. This is called hyponatremia and it can be life-threatening.

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• Office of Patient Education. The heat is on! Precautions for people with diabetes during the summer months. Mayo Clinic, 2018.
• Auerbach PS, et al., eds. Dehydration and rehydration. In: Auerbach's Wilderness Medicine. 7th ed. Elsevier; 2017. https://www.clinicalkey.com. Accessed Oct. 9, 2020.
• Water & nutrition. U.S. Centers for Disease Control and Prevention. https://www.cdc.gov/healthywater/drinking/nutrition/index.html. Accessed Oct. 2, 2020.
• Dietary reference intakes for electrolytes and water. U.S. National Academies of Science, Engineering, and Medicine. https://www.nationalacademies.org/our-work/dietary-reference-intakes-for-electrolytes-and-water. Accessed Oct. 2, 2020.
• Franklin BA. Exercise prescription and guidance for adults. https://www.uptodate.com/contents/search. Accessed Oct. 2, 2020.
• High-altitude travel & altitude illness. U.S. Centers for Disease Control and Prevention. https://wwwnc.cdc.gov/travel/yellowbook/2020/noninfectious-health-risks/high-altitude-travel-and-altitude-illness. Accessed Oct. 2, 2020.
• Bardosono S, et al. Pregnant and breastfeeding women: Drinking for two. Annals of Nutrition & Metabolism. 2017; doi:10.1159/000462998.
• Sterns RH. Maintenance and replacement fluid therapy in adults. https://www.uptodate.com/contents/search. Accessed Oct. 2, 2020.
• Gordon B. How much water do you need. Academy of Nutrition and Dietetics. https://www.eatright.org/food/nutrition/healthy-eating/how-much-water-do-you-need. Accessed Oct. 2, 2020.
• 10 tips: Make better beverage choices. U.S. Department of Agriculture. https://www.choosemyplate.gov/ten-tips-make-better-beverage-choices. Accessed Oct. 2, 2020.
• Thomas DT, et al. Position of the Academy of Nutrition and Dietetics, Dietitians of Canada, and American College of Sports Medicine: Nutrition and athletic performance. Medicine & Science in Sports & Exercise. 2016; doi:10.1016/j.jand.2015.12.006.
• Armstrong LE, et al. Water intake, water balance, and the elusive daily water requirement. Nutrients. 2018; doi:10.3390/nu10121928.

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Drinking Water

Eat Well & Keep Moving

Cheung LWY, Dart H, Kalin S, Otis B, Gortmaker SL. Eat Well & Keep Moving: An Interdisciplinary Elementary Curriculum Nutrition and Physical Activity (Third Edition) . Human Kinetics, Champaign, Illinois, 2016.

Newsletter Handouts Newsletter handouts to send home (educators can send home these sample newsletters to inform parents and complement the Eat Well & Keep Moving lesson topic being taught in the classroom). Newsletter handouts related to drinking water: – Stay Cool – Be Sugar Smart

Trainings Training Workshop for Food Service Staff Six training modules for food service staff provide an overview of the Eat Well & Keep Moving program, focusing on the role of food services in making the link between classroom and cafeteria. An additional lunch break demonstrates some cafeteria dishes.  

Learn more about  Eat Well & Keep Moving   here .

Food & Fun After School

Full, 600-page Food & Fun After School curriculum This curriculum includes all units, planning tools, recipes, and parent materials. Units related to drinking water: – Unit 3: Sugar Sweetened Drinks—Be Sugar Smart! – Unit 10: Hydration—Be Active, Stay Cool! – Unit 11: Food & Fun Finale!

Staff Training Food & Fun After School has several training strategies to help afterschool staff learn about and implement the curriculum, including training videos .

Parent Handouts These handouts – available in English, Spanish, and Chinese – include topic area information and tips for success for parents to create healthier environments for their children. Parent handouts related to drinking water: – Hydration

Learn more about Food & Fun After School here .

Planet Health

Citation: Carter J, Wiecha JL, Peterson KE, Nobrega S, Gortmaker SL. Planet Health: An Interdisciplinary Curriculum for Teaching Middle School Nutrition and Physical Activity (Second Edition) . Champaign, Illinois: Human Kinetics; 2007.

Learn more about  Planet Health here .

Out-of-School Nutrition and Physical Activity (OSNAP) Initiative

Tip Sheets These tip sheets, informed by out-of-school/afterschool program experiences, can help afterschool and other out-of-school-time programs make sustainable changes to program practices. They are practical guides designed to simplify healthy changes and describe promising practices for out-of-school/afterschool staff. OSNAP tip sheets related to drinking water: – Water, Water Everywhere! – Sugar-Sweetened Beverages – Healthy Staff, Healthy Kids!

Learn more about OSNAP here .

HPRC Water Access Scan Tool for Schools This tool can be helpful for assessing the availability of water fountains, water coolers, hydration stations, and other sources of free water.

Keep it Flowing: A Practical Guide to School Drinking Water Planning, Maintenance, & Repair This guide addresses the practical side of drinking water in schools by outlining the steps needed to provide adequate numbers of properly maintained drinking fountains and tap water dispensers in school buildings. It is designed for the people who make our nation’s schools run day-in and day-out, including those within state and tribal agencies and organizations, districts, school boards and local education authorities and schools.

Grab a Cup, Fill it Up! Simple posters encouraging students to drink water and directing them to a water source location. These posters were used in a school-based cafeteria intervention that provided disposable cups near water fountains.

Childhood Obesity Intervention Cost-Effectiveness Study (CHOICES) Project

>>Featured resource : Strategy Profile: Promoting Water Consumption in Schools Promoting water consumptions in school involves increasing water consumption among elementary and middle school students (grades K-8) with the installation of chilled drinking water dispensers in school cafeterias with viable plumbing in schools that participate in the National School Lunch Program. This profile describes the estimated benefits, activities, resources, and leadership needed to implement this strategy, which can be useful for planning and prioritization purposes.

Learn more about the CHOICES Project here  and  browse more tools & guides related to drinking water in the CHOICES Resource Library .

Food & Fun & Family

A Guide to Help Busy Families Develop Healthier Habits at Home This guide contains lots tips and ideas for meals and activities that are healthy and fun for the whole family.

Recipe Packet This recipe packet contains fun, healthy, and inexpensive recipes that are quick to prepare for both snack and dinner time.

Learn more about Food & Fun here .

Fast Maps These tools are designed to help out-of-school/afterschool program staff overcome systematic challenges that go beyond the site level. For example, addressing issues of limited space for physical activity in out-of-school/afterschool programs might involve meeting with school principals or partnering with nearby community spaces. OSNAP Fast Maps related to drinking water: – Improving Water Consumption – Eliminating Sugary Drinks from Snacks Served

Practice Assessment Tool This form can help out-of-school/afterschool program staff see where their program is currently at regarding the OSNAP standards. This form will help identify areas an organization can take action on to improve the health of kids.

Policy Writing Guide This guide provides suggestions for language that can be directly inserted into parent or family handbooks, staff handbooks, general program handbooks, letters to families, staff training materials, or even schedules and menus. This can be used to write a policy for eliminating sugary drinks from being served and providing access to water.

Additional resources for healthy snacks and beverages , including a water pitcher sanitation guide .

Massachusetts CHOICES (MA-CHOICES) Project

Research Brief: Massachusetts: Water Dispensers in Schools – View as an accessible webpage – Download as a PDF

Research Brief: Boston, MA: Creating Healthier Afterschool Environments (OSNAP) – View as an accessible webpage – Download as a PDF

Learn more about the MA-CHOICES project here .

>>Featured resource : Brief: Improving Drinking Water Equity and Access in California Schools This brief summarizes a CHOICES Learning Collaborative Partnership model examining a strategy to improve access to drinking water in California schools. This voluntary water equity and access program involves the installation of touchless chilled water dispensers on or near school cafeteria lunch lines in K-8 non-charter California public schools that have adequate plumbing.

Learn more about the CHOICES Project here  and  browse more research briefs & reports related to drinking water in the CHOICES Resource Library .

Safe Home Drinking Water

Case Study Briefs These research briefs highlight findings from an assessment of state and local programs and policies for home water quality testing, home well water treatment device installation, filter pitcher distribution, and lead service line replacement: -Executive Summary & all six case study briefs: All -Individual files: – Safe Home Drinking Water: A Series of Six Case Study Briefs – Executive Summary – New Jersey Private Well Testing Act – New Hampshire & Vermont Private Well Testing Via Primary Care Clinics – The NH Water Well-Ness Initiative to Protect Pregnant WIC Participants from Contaminants in Private Well Water – Porterville, CA: Point-of-Use Filtration & Bottled Water Delivery Pilot Program to Protect Pregnant People and Infants from Nitrates in Private Well Water – Cincinnati Enhanced Lead Program to Replace Lead Service Lines – Denver Water Filter Program

Learn more about the Safe Home Water project here .

Early Adopters: State Approaches to Testing School Drinking Water for Lead in the United States

These research briefs & full report take a closer look at states’ efforts related to testing school drinking water for lead. – Full research report: Early Adopters: State Approaches to Testing School Drinking Water for Lead in the United States – Healthy Eating Research Brief: Early Adopters: State Approaches to Testing School Drinking Water for Lead in the United States

Learn more about the Early Adopters project here .

AJPH Podcast, Sept 2017 – Water Access & Health Disparities in the U.S. Lead author Carolyn Brooks, Dr. Anisha Patel, and Kelley Dearing-Smith discuss a massive public health problem which is rarely mentioned and probably underestimated — unequal access to water in the United States –in this podcast with the American Journal of Public Health hosted by Alfredo Morabia. Learn more about this research here .

The Nutrition Source , Harvard T.H. Chan School of Public Health – Healthy Drinks – Water

National Drinking Water Alliance

Division of Nutrition, Physical Activity and Obesity (DNPAO) , Centers for Disease Control and Prevention (CDC)

CDC Healthy Schools Water Acces s, Centers for Disease Control and Prevention (CDC)

Nutrition and Obesity Policy Research and Evaluation Network (NOPREN)

3Ts for Reducing Lead in Drinking Water Toolkit, 2018 , United States Environmental Protection Agency

RWJF Healthy Eating Research

Team Nutrition , United States Department of Food and Agriculture (USDA) Food and Nutrition Service

Strategies for Improving Access to Drinking Water in Schools , Centers for Disease Control and Prevention and Bridging the Gap Research Program

Water Access in Schools , Centers for Disease Control and Prevention

Healthy Hunger-Free Kids Act , USDA Food and Nutrition Service

Water Availability During NSLP Meal Service , USDA Food and Nutrition Service

Last updated:  April 17, 2024

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Drinking Water Publications

At a glance.

Explore our toolkits, guides, and scientific publications about drinking water. Topics include private wells, performance improvement, and emergency preparedness and response.

Centers for Disease Control and Prevention. Community health impact of extended loss of water service — Alabama, January 2010 . MMWR. 2011;60(6):161-6. (Miller M, Otto C)

Centers for Disease Control and Prevention and American Water Works Association. Emergency water supply planning guide for hospitals and health care facilities . Atlanta: U.S. Department of Health and Human Services; 2019.

Centers for Disease Control and Prevention and American Water Works Association. Drinking water advisory communication toolbox . Atlanta: U.S. Department of Health and Human Services; 2013.

Centers for Disease Control and Prevention, U.S. Environmental Protection Agency, National Oceanic and Atmospheric Agency, and American Water Works Association. When every drop counts: protecting public health during drought conditions—a guide for public health professionals. Atlanta: U.S. Department of Health and Human Services; 2010.

Curtiss E, Hils J, Rokisky J. Keep your water safe with CDC's resources. [commentary] J Environ Health. 2022;84(10):42-3.

Galbraith R, Sharp N, Sandoval D. Collaborative response to natural disaster events threatening private well water quality in a New Mexico community. [commentary] J Environ Health. 2019;81(10):36-8.

Hubbard B, Sabogal R, Zarate-Bermudez M. Community resources for contaminants of concern in private wells. [commentary] J Environ Health. 2023;85(7):36-8.

Jackson BR, Zegarra JA, López-Gatell H, Sejvar J, Arzate F, Waterman S, et al. Binational outbreak of Guillain-Barré syndrome associated with Campylobacter jejuni infection, Mexico and USA, 2011. Epidemiol Infect. 2013 Aug 7:1-11. [Epub ahead of print] [Zárate-Bermúdez M, Sabogal R]

Lauper U, Zartarian M, Hogan C, Savage B, Dziewulski D. Creating a comprehensive data set of private wells and well vulnerability in New York. [commentary] J Environ Health. 2020;82(7):30-2.

Lee Pow Jackson C, Zarate-Bermudez M. Exposure to contaminants among private well users in North Carolina: Enhancing the role of public health. [commentary] J Environ Health. 2019;81(8):36-8.

McClenahan S, Hubbard B. Safe Water for Community Health update. [commentary] J Environ Health. 2019;81(6):31-4.

Neset K, Ritter T, Hanson R, Hargrove R. Effective partnering to increase access to water on the Navajo Nation . The Military Engineer. 2022;737:62-65.

Sabogal R. Making data-driven decisions for safe water. [commentary] J Environ Health. 2021;84(3):38-40.

Sabogal R, Kalis M, Hubbard B, Oeffinger J, Baddour LJ, Tate C, et al. Innovative Safe Water Program Improvement e-learning for environmental health professionals. [commentary] J Environ Health. 2018;80(10):38-40.

Zarate-Bermudez M, Dye S. Benefits of collaboration between a county health department and a local university in North Carolina. [commentary] J Environ Health. 2018;81(3):32-5.

Environmental Health Services

Environmental health programs deliver important environmental health services in their communities to protect health where we live, work, and play.

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UW Associate Professor’s Hydration Research Featured in Prominent Fitness Magazine

• News Releases
• Back to 2023 Archive

Institutional Communications Bureau of Mines Building, Room 137 Laramie, WY 82071 Phone: (307) 766-2929 Email:   [email protected]

Published May 15, 2024

For most of us, taking a drink of water when we’re thirsty may seem like an afterthought. However, recently published research by a University of Wyoming faculty member indicates that adequate water intake and one’s “hydration status” are not equally experienced by the public in general and lacking adequate hydration can have adverse effects on our health and especially that of certain populations.

Evan Johnson, an associate professor in the Division of Kinesiology and Health in the College of Health Sciences, along with two other academic researchers in hydration studies, had his manuscript, titled “ Is mild dehydration a risk for progression of childhood chronic kidney disease? ,” published in Pediatric Nephrology , the journal of the International Pediatric Nephrology Association.

Following the manuscript’s publication, additional insights related to adult water intake provided by Johnson were quoted in “The Thirst Trap,” the featured article in the April edition of Men’s Health magazine.

Johnson’s research interests include examining the physiological mechanisms and overall health benefits related to optimal hydration, physical activity and heat exposure.

Johnson’s published research looked specifically at children with chronic kidney disease (CKD) and their having, in some cases, an inherent vulnerability to dehydration. Very young children and infants with CKD -- who cannot access water freely on their own -- may face certain risk factors and consequences when experiencing mild dehydration and underhydration with CKD. The research also examined evidence for the risk of CKD progression in these children.

“I am excited to be included with my co-authors on this paper because it highlights the serious health risks that can be due to underhydration/dehydration, especially within some of the most vulnerable populations,” Johnson says. “Within the medical community, there is a double-edged sword related to the success of our physiology which, in large part, maintains water balance and homeostasis through regulation of what and how quickly our kidneys filter our blood. 

“The positive is that the additional stress placed on our kidneys when fluid intake is too low acutely, in most cases, produces minimal health effects,” Johnson continues. “On the other lesser-known hand, with persistent stress to the kidney, potentially life-threatening conditions, such as chronic kidney disease, are more likely to occur. My hope with this publication is that practitioners become more aware and understanding of the repercussions of inadequate hydration in children.”

While published research on dehydration and underhydration in children with CKD is limited, Johnson’s research notes that it is biologically plausible that these conditions could affect CKD progression. However, the question begs asking: Can other vulnerable populations be affected by short- and long-term exposure to dehydration and even overhydration occurrences?

That’s where the publishers of Men’s Health magazine took note of Johnson’s hydration research.

“The Thirst Trap” article looked not only at basic human hydration needs, but also at the possible hazards of the misuse of drinking water, such as water fasting, overconsumption and the potential for even life-threatening conditions resulting from such misuse.

“Drinking too much water is not safe and can result in serious complications, such as seizures, brain swelling and even death,” cited a source in the article.

Another source pointed out that a large portion of the population is experiencing frequent and sometimes long-term underhydration that can have negative health effects, while others have taken to overhydrating, bringing on the same level of health risks.

Where is the balance in water consumption?

Men’s Health magazine points to the National Academy of Sciences’ official guidelines on hydration, which recommend 3.7 liters of fluid per day for men and 2.7 liters of fluid per day for women. This amounts to 127 ounces, or just under a gallon for men, and 90 ounces for women, but not consumed all at once.

Johnson puts an even finer point to this, adding, “The exception to this is the elderly, whose feedback mechanisms regulating total body water homeostasis are more likely to be disrupted and could probably benefit from an extra glass or two of water each day.”

If a person is regularly undertaking intense, multihour bouts of training or endurance sports, Johnson recommends a hydration plan. That way, the individual won’t be dehydrated or overdrink.

Adding to the Men’s Health article, Johnson explains the importance of an athlete implementing a hydration plan.

The first step is for a person to weigh themself before an intense, hourlong session of exercise or similar activity. During the workout, that individual would track the volume of water they drink, he says.

After the workout, the person would weigh themself to calculate weight loss, or a negative value, from the workout. Then, if fluid was consumed during the workout, the person would subtract the weight of the beverage from weight loss results in the total sweat loss, a more negative value, Johnson explains. Reconverting the weight lost into water volume would give the volume of fluid lost. Dividing that volume over the duration of the exercise session provides the rate of body water loss, Johnson says.

That person then would know how much they sweat in an hour in those conditions and how much water they would need to drink to replace that water loss and stay hydrated. A hydration plan is especially useful during long races, such as marathons, Johnson says.

Other individuals who could benefit from a hydration plan are those who can’t drink or urinate regularly during their jobs, such as nurses, teachers and firefighters.

“My absolute favorite quotation related to my field is from Hippocrates, who is thought to have said, ‘If we could give every individual the right amount of nourishment and exercise, not too little and not too much, we would have found the safest way to health,’” Johnson says. “I’m excited to continue my research to further define the details of what too little or too much is and the context related to these recommendations.”

To view the Men’s Health magazine article, go to www.menshealth.com/health/a60249105/how-much-water-to-drink-water-obsession/ .

About the University of Wyoming College of Health Sciences

UW’s College of Health Sciences trains health and wellness professionals and researchers in a wide variety of disciplines, including medicine, nursing, pharmacy, speech-language pathology, social work, kinesiology, public health, health administration and disability studies. The college also oversees residency and fellowship programs in Casper and Cheyenne, as well as operating a speech/hearing clinic in Laramie and primary care clinics in Laramie, Casper and Cheyenne.

With more than 1,600 undergraduate, graduate and professional students, the college is dedicated to training the health and wellness workforce of Wyoming and conducting high-quality research and community engagement, with a particular focus on rural and frontier populations.

• Diet & Nutrition

8 Ways to Stay Hydrated if You Hate Drinking Water

F or all the hype surrounding status water bottles —looking at you, Stanley and Owala—it turns out many of us aren’t drinking nearly enough H2O. “It’s a struggle,” says Vanessa King, a registered dietitian nutritionist with Queen’s Health System in Oahu, Hawaii. “We see thousands of people a month, and drinking enough water comes up all the time.”

Exactly how much you need to drink every day depends on a variety of factors, including your age, activity level, how much you sweat, and your health status, as well as which medications you take (some can cause dehydration) and your location (hot places call for more water). One rule of thumb, King says, is to drink half your weight in water (in ounces) every day. For example, if you weigh 140 pounds, your target would be 70 ounces—or at least eight 8-ounce glasses—per day. To zero in on a more specific number, she advises talking to your doctor or a registered dietitian.

If you’re not getting enough water, you’ll be able to tell: Your mouth might get dry, King says, and your pee will become darker than normal. You might get a headache or feel dizzy. Plus, you’ll feel thirsty. People who are truly dehydrated—which is common among older adults—can experience altered mental status, hypotension, kidney failure, and other complications that may require hospitalization. 

Being well-hydrated, on the other hand, is linked to improved mood and cognition , as well as optimal physical performance . It can aid weight loss , alleviate constipation , and even make your skin look healthier . If you're drinking the right amount of water, “there’s only positives,” says Maya Feller, a registered dietitian nutritionist based in Brooklyn and author of Eating from Our Roots: 80+ Healthy Home-Cooked Favorites from Cultures Around the World . “There’s just so many benefits.”

But realistically, how do you glug all that water (especially if it's far from your favorite beverage)? We asked experts to share how they manage to drink enough every day.

Add one glass per week

Lots of people avoid drinking water because they don’t want to have to make frequent beelines to the bathroom during the workday. Easing into it, however, can teach your body to tolerate a new level of water intake. “I encourage people to have that first glass as close to waking up as possible, because if they’re going to go to the bathroom, it’s going to happen at home and not on their commute or when they get to the office,” Feller says. After a week, add in an extra glass when you get home from work, which will allow your body to adjust to two additional glasses per day. Then, in week three, add an additional glass at any point during the day. “Keep going until you get to your desired amount,” Feller says, giving your body a week to adjust to each new glass of water.

Schedule nudges throughout the day

If you routinely forget to drink enough water, consider enlisting technological assistance. “Phone reminders are a very cool thing,” says Melanie Betz, a registered dietitian in Chicago who specializes in renal and geriatric nutrition. Lots of apps offer the ability to schedule hydration nudges throughout the day.

Read More : What Experts Really Think About Diet Soda

For people who want a fancy, high-tech solution, Betz sometimes recommends a HidrateSpark “smart” water bottle , which tracks how much you drink—and starts glowing when you haven’t had enough. It can also send reminders to your phone when you haven’t had any water in a certain amount of time. Or, of course, you can keep things simple and set alarms for, say, 9 a.m., noon, 3 p.m., and 6 p.m., she says. That way, your smartwatch will vibrate or your phone will ding when it’s time to drink.

Start a water log

Any time you’re trying to make a lifestyle change, it helps to have a specific goal, Betz points out. Pledging to drink 100 ounces of water a day, for example, is more effective than thinking, “I’ll start drinking more water,” she says. It can be hard to keep track of your intake throughout the day, so consider starting a Notes app memo where you list how much you drank, and at what time. That will help reveal patterns and let you know where you could make changes, she says; you might notice you don’t drink much in the morning, for instance. And remember, It takes time to develop a new habit. “Give yourself some grace,” Betz says—you’re not going to jump from 16 ounces to 64 overnight.

Add herbs to your water or ice cubes

If you find water boring—and let’s be real, it can be—experiment with fun ways to jazz it up. King likes adding “flavor enhancers” such as slices of lemon and lime and chunks of pineapple. “It becomes very tropical,” she says. Or prepare a glass of cucumber water: Drop sliced cucumbers into your water, along with some ginger and mint. “It looks pretty and makes it more inviting,” King says. “Plus it’s something your friends can get on board with when they come over and drink water.”

Read More : Your Brain Doesn't Want You to Exercise

Betz enjoys testing out different herbs. One of her favorite concoctions is water infused with watermelon and basil, which she finds much more interesting than plain. Blackberry and rosemary also work well, she says, and feel fancy.

Speaking of elevated options: Feller suggests treating yourself to herb-filled ice cubes. Choose a couple of your favorites, like basil and mint, and then mash them up or mince them before adding them to an ice-cube tray. Pour water on top, freeze, and enjoy. “It’s so good, and it makes the drink pretty,” she says.

Ditch the colorful water bottles

Invest in a clear water bottle, and always carry it with you, King suggests. “A lot of people who carry water bottles carry them home full,” she says. “A clear one lets you see how you’re doing.” If a completely full bottle is in your face all day, after all, you’ll probably get the hint that it’s time to take a sip.

Another way to increase visibility, King says, is to put a glass of water on your bedside table. That way, you can make drinking water first thing in the morning a habit. It’s also helpful to keep pitchers of water on your kitchen counter and in other high-traffic areas.

Play with temperature

Feller works with people around the globe, and many don’t drink ice-cold water—they consider it “an American thing.” Regardless of where you live, you might find you prefer a different temperature, too. Leave your water out so it’s room temp, add some ice, or even boil it like you would tea, Feller advises. As you experiment with different temperatures, “you’ll find that it becomes a bit easier to drink once you know what temperature you prefer,” she says.

Pretend you’re a plant

The app Plant Nanny makes drinking fun, says King, who’s recommended it to her patients. Once you download it, you’ll become responsible for virtual plants; each time you log that you’ve had a glass of water, your plants will be watered, too. “When I first tested it out, I turned it on and my plant was wilted,” King recalls. “And it was super cute. I was immediately emotionally attached to it—you forget it’s not a real plant.” That made her want to meet her daily hydration goals, she says, noting that the app is a good fit for parents helping their kids understand the importance of staying well-hydrated.

Read More : Your Houseplants Have Some Powerful Health Benefits

Expand your definition of “water”

Chugging glassfuls of water isn’t the only way to hydrate. Dairy and dairy alternatives, like almond milk and soy milk, also contain water, King points out; in fact, it's the first ingredient listed on labels.

And don’t overlook the role that fruits, vegetables, broths, soups, and stews can play in your daily hydration goals. Some of the most water-heavy choices include melons like cantaloupe and watermelon; berries such as strawberries; and leafy greens like spinach, cucumbers, and zucchini, King says. Other smart choices include bananas, pears, oranges, pineapples, carrots, broccoli, and avocados. “A good dose of fruits and vegetables in your day can also help with meeting your water target,” she says. So if you absolutely can’t stand the thought of one more glass of water, consider consuming it a tastier way instead.

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Drinking Water Quality and Human Health: An Editorial

Patrick levallois.

1 Direction de la santé environnementale et de la toxicologie, Institut national de la santé publique du Québec, QC G1V 5B3, Canada

2 Département de médecine sociale et préventive, Faculté de médecine, Université Laval, Québec, QC G1V 0A6, Canada

Cristina M. Villanueva

3 ISGlobal, 08003 Barcelona, Spain; [email protected]

4 Universitat Pompeu Fabra (UPF), 08002 Barcelona, Spain

5 Consortium for Biomedical Research in Epidemiology and Public Health (CIBERESP), Carlos III Institute of Health, 28029 Madrid, Spain

6 IMIM (Hospital del Mar Medical Research Institute), 08003 Barcelona, Spain

Drinking water quality is paramount for public health. Despite improvements in recent decades, access to good quality drinking water remains a critical issue. The World Health Organization estimates that almost 10% of the population in the world do not have access to improved drinking water sources [ 1 ], and one of the United Nations Sustainable Development Goals is to ensure universal access to water and sanitation by 2030 [ 2 ]. Among other diseases, waterborne infections cause diarrhea, which kills nearly one million people every year. Most are children under the age of five [ 1 ]. At the same time, chemical pollution is an ongoing concern, particularly in industrialized countries and increasingly in low and medium income countries (LMICs). Exposure to chemicals in drinking water may lead to a range of chronic diseases (e.g., cancer and cardiovascular disease), adverse reproductive outcomes and effects on children’s health (e.g., neurodevelopment), among other health effects [ 3 ].

Although drinking water quality is regulated and monitored in many countries, increasing knowledge leads to the need for reviewing standards and guidelines on a nearly permanent basis, both for regulated and newly identified contaminants. Drinking water standards are mostly based on animal toxicity data, and more robust epidemiologic studies with an accurate exposure assessment are rare. The current risk assessment paradigm dealing mostly with one-by-one chemicals dismisses potential synergisms or interactions from exposures to mixtures of contaminants, particularly at the low-exposure range. Thus, evidence is needed on exposure and health effects of mixtures of contaminants in drinking water [ 4 ].

In a special issue on “Drinking Water Quality and Human Health” IJERPH [ 5 ], 20 papers were recently published on different topics related to drinking water. Eight papers were on microbiological contamination, 11 papers on chemical contamination, and one on radioactivity. Five of the eight papers were on microbiology and the one on radioactivity concerned developing countries, but none on chemical quality. In fact, all the papers on chemical contamination were from industrialized countries, illustrating that microbial quality is still the priority in LMICs. However, chemical pollution from a diversity of sources may also affect these settings and research will be necessary in the future.

Concerning microbiological contamination, one paper deals with the quality of well water in Maryland, USA [ 6 ], and it confirms the frequent contamination by fecal indicators and recommends continuous monitoring of such unregulated water. Another paper did a review of Vibrio pathogens, which are an ongoing concern in rural sub-Saharan Africa [ 7 ]. Two papers focus on the importance of global primary prevention. One investigated the effectiveness of Water Safety Plans (WSP) implemented in 12 countries of the Asia-Pacific region [ 8 ]. The other evaluated the lack of intervention to improve Water, Sanitation and Hygiene (WASH) in Nigerian communities and its effect on the frequency of common childhood diseases (mainly diarrhea) in children [ 9 ]. The efficacies of two types of intervention were also presented. One was a cost-effective household treatment in a village in South Africa [ 10 ], the other a community intervention in mid-western Nepal [ 11 ]. Finally, two epidemiological studies were conducted in industrialized countries. A time-series study evaluated the association between general indicators of drinking water quality (mainly turbidity) and the occurrence of gastroenteritis in 17 urban sites in the USA and Europe. [ 12 ] The other evaluated the performance of an algorithm to predict the occurrence of waterborne disease outbreaks in France [ 13 ].

On the eleven papers on chemical contamination, three focused on the descriptive characteristics of the contamination: one on nitrite seasonality in Finland [ 14 ], the second on geogenic cation (Na, K, Mg, and Ca) stability in Denmark [ 15 ] and the third on historical variation of THM concentrations in french water networks [ 16 ]. Another paper focused on fluoride exposure assessments using biomonitoring data in the Canadian population [ 17 ]. The other papers targeted the health effects associated with drinking water contamination. An extensive up-to-date review was provided regarding the health effects of nitrate [ 18 ]. A more limited review was on heterogeneity in studies on cancer and disinfection by-products [ 19 ]. A thorough epidemiological study on adverse birth outcomes and atrazine exposure in Ohio found a small link with lower birth weight [ 20 ]. Another more geographical study, found a link between some characteristics of drinking water in Taiwan and chronic kidney diseases [ 21 ]. Finally, the other papers discuss the methods of deriving drinking water standards. One focuses on manganese in Quebec, Canada [ 22 ], another on the screening values for pharmaceuticals in drinking water, in Minnesota, USA [ 23 ]. The latter developed the methodology used in Minnesota to derive guidelines—taking the enhanced exposure of young babies to water chemicals into particular consideration [ 24 ]. Finally, the paper on radioactivity presented a description of Polonium 210 water contamination in Malaysia [ 25 ].

In conclusion, despite several constraints (e.g., time schedule, fees, etc.), co-editors were satisfied to gather 20 papers by worldwide teams on such important topics. Our small experience demonstrates the variety and importance of microbiological and chemical contamination of drinking water and their possible health effects.

Acknowledgments

Authors want to acknowledge the important work of the IJERPH staff and of numbers of anonymous reviewers.

Author Contributions

P.L. wrote a first draft of the editorial and approved the final version. C.M.V. did a critical review and added important complementary information to finalize this editorial.

This editorial work received no special funding.

Conflicts of Interest

The authors declare no conflict of interest.

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Water Intoxication: What Happens When You Drink Too Much Water?

Exploring the Risks and Consequences of Excessive Water Intake

• Water Intoxication Effects
• Signs and Symptoms
• What Is Too Much?
• Daily Water Needs

Water intoxication, also known as water poisoning, is when you drink more water than your body can process. Drinking too much water by accident is difficult, but it can happen, usually from drinking excessively while participating in sports or intense training.

Symptoms of water intoxication can be nonspecific (vague) and may include confusion, disorientation, nausea, and vomiting. In rare cases, it can also cause brain swelling, which can become fatal.

This article reviews the potential causes of water intoxication, signs, and treatment.

Nastasic / Getty Images

What Happens If You Drink Too Much Water?

Drinking too much water can result in water intoxication. Overhydration occurs when the body's volume of water becomes more than the kidneys can process and excrete. It can lead to an imbalance of electrolytes (minerals in the blood and other body fluids that carry an electric charge), such as sodium (salt). 

Sodium helps maintain water balance in and around the body's cells. The balance is important for muscle and nerve function and maintaining blood pressure levels. When sodium levels are diluted in the blood ( hyponatremia ), fluids move from the blood to the cells.

This increase of water within the cells can lead to various health problems.

Signs You Are Drinking Too Much Water

Signs and symptoms of drinking too much water can be hard to pinpoint, especially if they occur gradually over time. Signs and symptoms may include:

• Clear or colorless urine
• Nausea and vomiting
• Confusion or disorientation
• Muscle cramps
• Drowsiness or fatigue

In severe cases, water intoxication can lead to seizures or a loss of consciousness.

What Causes Water Intoxication?

Water intoxication in healthy people is rare, though it can happen. Drinking too much water is one common cause, though certain medical conditions and improper rehydration can lead to water intoxication, as well.

Endurance athletes, such as those who participate in marathons (26.2-mile run or walk), ultramarathon (longer than a marathon run or walk), Ironman or triathlon events (run, bike, and swim), hiking, or elite rowing, may be at risk for water intoxication if they drink large amounts of water prior to and during physical activity.

Drinking a lot of water after prolonged exercise repletes water reserves, but does not correct electrolyte losses that occurred during exercise. This can result in electrolyte imbalances in the blood, leading to water intoxication.

Military Training

Military members involved in intense training exercises may experience water toxicity the same as endurance athletes or people who engage in highly intense sports.

Drug Interactions

Some drugs may make you extremely thirsty and cause hyponatremia.

These include:

• 3,4-methyl​enedioxy​methamphetamine (MDMA, also known as ecstasy or molly) and other phenethylamines
• Antipsychotic drugs (reduce symptoms of psychosis, which affects the mind)
• Diuretics (medications that reduce fluid buildup)

Mental Health Conditions

Craving water excessively due to a persistent sensation of thirst is known as psychogenic polydipsia . For example, this is sometimes seen in people with schizophrenia .

Can You Die From Drinking Too Much Water?

Though rare, there have been reported cases of people dying from drinking too much water. Electrolyte imbalances that are severe or prolonged, it can lead to seizures, loss of consciousness, and coma . Swelling of the brain may then occur and can be fatal if not promptly treated.

How Much Water Is Too Much?

There isn’t a set amount of water that is too much for the general population. A person’s age, sex, health status, and physical activity levels all play a role in determining how much water their body can process.

The kidneys of a healthy adult can process around 20 to 28 liters (5 to 7 gallons) of water in a day, with the ability to excrete only 0.8 to 1 liter per hour (27 to 33 fluid ounces). Because of this, water intake in healthy adults should not exceed this amount.

Water intoxication can happen more quickly in older adults, children, or those with certain medical conditions such as kidney disease or heart failure . This is because their kidneys may not be as efficient in processing a higher volume of water. The amount of water they can safely drink may be lower.

Always consult a healthcare provider for guidance on what amount of water is safe for you per day.

How Much Water Do You Need Each Day?

There is no official recommendation for how much plain water everyone should drink per day . However, in 2005 the Institute of Medicine released a dietary reference intake for water consumed from all beverages and foods in a day.

The recommended amounts vary depending on your age, sex, pregnancy status, and lactation (breastfeeding or chestfeeding) status. For example, the adequate intake (AI) for total water intake (from all beverages and foods) for men and women ages 19 to 30 years is 3.7 liters and 2.7 liters per day, respectively.

In general, it’s best to drink to thirst (drink when you feel thirsty). The color of your urine can also be a good indicator of hydration status. Aim for urine color that is pale yellow or the color of lemonade. Clear urine may indicate you are drinking too much water, or don’t need to drink any more water for a little while. 

For some people, drinking half your body weight (in pounds) in ounces may be a good starting point. For example, someone who weighs 200 pounds might want to aim for 100 ounces of water per day.

However, keep in mind that this is not an official recommendation but rather a general rule to help guide water intake per day. Individual water needs will vary from person to person depending on other factors such as age, sex, health status, temperature conditions, and activity levels.

While drinking enough water per day is important , staying within the recommended range can help prevent overhydration and possible water intoxication.

A Note on Gender and Sex Terminology

Verywell Health acknowledges that  sex and gender  are related concepts, but they are not the same. To accurately reflect our sources, this article uses terms like “female,” “male,” “woman,” and “man” as the sources use them.

How Is Water Intoxication Treated?

Treatment for water intoxication will depend on the severity and the underlying cause. Along with treating any underlying cause(s), water intoxication treatments may include:

• Fluid restriction
• Electrolyte replacement
• Diuretic medication to increase urination
• Medical interventions in severe cases

Water intoxication is when you drink more water than your body is able to process. Water intoxication is rare. Causes of water intoxication include drinking large amounts of water with extreme activity, taking certain medications, or having certain medical conditions.

Signs and symptoms can be vague but may include clear or colorless urine, headache, nausea and vomiting, confusion or disorientation, muscle cramps, and drowsiness or fatigue.

Water intoxication treatment will vary depending on the severity and underlying cause and may include fluid restriction, electrolyte replacement, medications to increase urination, or other medical interventions in severe cases.

How much water you can safely drink in a day depends on several factors, such as age, sex, weight, health status, and activity levels. Urine color may be a good indicator of hydration status, with a goal of having pale yellow urine. Always talk with a healthcare provider for more individualized water intake recommendations. 

Siegel AJ. Fatal water intoxication and cardiac arrest in runners during marathons: prevention and treatment based on validated clinical paradigms . Am J Med . 2015;128(10):1070-1075. doi:10.1016/j.amjmed.2015.03.031

Hoorn EJ, Zietse R. Diagnosis and treatment of hyponatremia: compilation of the guidelines . J Am Soc Nephrol . 2017;28(5):1340-1349. doi:10.1681/ASN.2016101139

Lee LC, Noronha M. When plenty is too much: water intoxication in a patient with a simple urinary tract infection . BMJ Case Rep. 2016;2016:bcr2016216882. doi:10.1136/bcr-2016-216882

Hew-Butler T, Loi V, Pani A, Rosner MH. Exercise-associated hyponatremia: 2017 update . Front Med (Lausanne) . 2017;4:21. doi:10.3389/fmed.2017.00021

Faria AC, Carmo H, Carvalho F, Silva JP, Bastos ML, Dias da Silva D. Drinking to death: hyponatraemia induced by synthetic phenethylamines . Drug Alcohol Depend . 2020;212:108045. doi:10.1016/j.drugalcdep.2020.108045

Gill M, McCauley M. Psychogenic polydipsia: the result, or cause of, deteriorating psychotic symptoms? A case report of the consequences of water intoxication . Case Rep Psychiatry . 2015;2015:846459. doi:10.1155/2015/846459

Hurwit AA, Parker JM, Uhlyar S. Treatment of psychogenic polydipsia and hyponatremia: a case report . Cureus . 2023;15(10):e47719. doi:10.7759/cureus.47719

Al-Juboori AN, Al Hail A, Ahmad Al-Juboori Z. Hyponatremia due to excessive water intake in COVID-19 patients: case series study . Egypt J Intern Med . 2022;34(1):71. doi:10.1186/s43162-022-00158-0

Joo MA, Kim EY. Hyponatremia caused by excessive intake of water as a form of child abuse . Ann Pediatr Endocrinol Metab . 2013;18(2):95-98. doi:10.6065/apem.2013.18.2.95

National Kidney Foundation. Hyponatremia (low sodium level in the blood) . 

Institute of Medicine. 2005. Dietary reference intakes for water, potassium, sodium, chloride, and sulfate. Washington, DC: The National Academies Press. https://doi.org/10.17226/10925.

Kenefick RW. Drinking strategies: planned drinking versus drinking to thirst . Sports Med . 2018;48(Suppl 1):31-37. doi:10.1007/s40279-017-0844-6

University of Missouri. How to calculate how much water you should drink .

By Brittany Poulson, MDA, RDN, CD, CDCES Poulson is a registered dietician and certified diabetes care and education specialist. She is based in Utah.

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• Published: 01 March 2024

Assessing exposure and health consequences of chemicals in drinking water in the 21st Century

• Nicole C. Deziel   ORCID: orcid.org/0000-0002-5751-9191 1 , 2 &
• Cristina M. Villanueva 2  

Journal of Exposure Science & Environmental Epidemiology volume  34 ,  pages 1–2 ( 2024 ) Cite this article

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Populations worldwide are exposed to a myriad of chemicals via drinking water, yet only a handful of chemicals have been extensively evaluated with regard to human exposures and health impacts [ 1 , 2 ]. Many chemicals are generally “invisible” in that they do not alter the color or odor of drinking water, and many of the associated effects are not observable for decades, making linkages between exposure and disease difficult. The articles included in the Journal of Exposure Science and Environmental Epidemiology Special Topic “Assessing Exposure and Health Consequences of Chemicals in Drinking Water in the 21st Century” cover a range of topics, including: (i) new exposure and health research for regulated and emerging chemicals, (ii) new methods and tools for assessing exposure to drinking water contaminants, (iii) issues of equity and environmental justice, (iv) drinking water issues within the context of a changing climate. This Special Topic includes articles authored by experts across multiple disciplines including environmental engineering, hydrology, exposure science, epidemiology, toxicology, climate science, and others. Many of these papers emerged from an international symposium organized by ISGlobal and Yale scientists held in Barcelona in September 2022 [ 3 ].

Regulated chemicals

Chemicals that have been the focus of environmental health research include disinfection by-products (DBPs), nitrate, and metals. Although many of these chemicals are regulated, there is concern about low-dose exposures at concentrations below standards and guidelines, and risks of health endpoints not yet studied. Kaufman et al. explore new ways to assess DBP exposure, considering concentrations and specific toxicity potential in relation to birth defects risk [ 4 ]. Long-term exposure to DBPs and nitrate is addressed by Donat-Vargas et al. in relation to chronic lymphocytic leukaemia in Spain [ 5 ]. Friedman et al. examine temporal and spatial variability of manganese concentrations in a case study in the United States (US) [ 6 ]. Hefferon et al. evaluated sociodemographic inequalities in fluoride concentrations across the US [ 7 ]. Spaur et al. evaluate the contribution of water arsenic to biomarker levels in a prospective study in the US [ 8 ].

Chemicals of emerging concern

Many emerging chemicals, such as per- and polyfluoroalkyl substances (PFAS), microplastics, and 1,4-dioxane, have drinking water as the dominant exposure pathway for many populations. Yet, these remain largely unregulated or have standards and guidelines that vary widely across states and countries. Because only small percentages of the universe of contaminants are regulated in drinking water, routine monitoring data for many chemicals of emerging concern is frequently absent or very limited. To advance understanding of drinking water exposures to PFAS, Cserbik et al. [ 9 ]. and Kotlarz et al. [ 10 ]. evaluate and compare PFAS in drinking water and blood serum samples in two different settings: an urban setting not impacted by PFAS pollution in Spain [ 9 ] and among well water users living near a fluorochemical facility in the US [ 10 ], respectively.

New methods and tools for exposure assessment

There is a need for improved tools, methods, and data to evaluate drinking water related exposures. These tools and techniques remain somewhat limited and lag behind those of other stressors (e.g., air pollution). Also, despite water contaminants occurring in mixtures, most of the evaluations (and policies and regulations) are conducted chemical by chemical, ignoring potential interactions. Schullehner et al. present case studies of three approaches of exposure assessment of drinking water quality: use of country-wide routine monitoring databases, wide-scope chemical analysis, and effect-based bioassay methods [ 11 ]. Luben et al. elaborate and compare different exposure assessment metrics to trihalomethanes in epidemiological analyses of reproductive and developmental outcomes [ 12 ]. Escher et al. present in vitro assays to evaluate biological responses of including neurotoxicity, oxidative stress, and cytotoxicity in different types of drinking water samples (tap, bottled, filtered) [ 13 ] Isaacs et al. present newly developed automated workflows to screen contaminants of concern based on toxicity and exposure potential [ 14 ]. Dorevitch et al. develop a novel method to improve detection of particulate lead spikes [ 15 ].

Issues of equity, environmental justice, and vulnerable populations

A substantial portion of the population (e.g., 20% in the United States) have private water supplies (e.g., a household domestic drinking water well), which are not subject to any federal regulatory oversight or monitoring [ 16 ]. This presents an equity issue in access to data on drinking water quality, as discussed in Levin et al. [ 2 ]. and heterogeneity in state-based policies for drinking water prevention, as discussed by Schmitt et al. [ 17 ]. Spaur et al. [ 8 ], observed that water from unregulated private wells and regulated municipal water supplies contributes substantially to overall exposures (as measured by urinary arsenic and uranium concentrations) in both rural, American Indian populations and urban, racially/ethnically diverse populations nationwide. Hefferon et al. evaluated environmental justice issues with respect to fluoride and found that 2.9 million US residents are served by public water systems with average fluoride concentrations exceeding the World Health Organization’s guidance limit [ 7 ]. Friedman et al. show that manganese in drinking water frequently exceeds current guidelines in the US, and occur at concentrations shown to be associated with adverse health outcomes, especially for vulnerable and susceptible populations like children [ 6 ].

Chemical contamination may also pose a serious threat in the developing world. Today, around 2.2 billion people – or 1 in 4 – still lack safely managed drinking water at home [ 18 ]. In most of the world, microbial contamination is the biggest challenge. Because it has been understudied, the chemical risks remain obscure [ 19 ], and regulators often require local data to take action. Praveena et al. reviews the quality of different drinking water types in Malaysia (tap water, ground water, gravity feed system) and its implications on policy, human health, management, and future research [ 20 ].

Water quality in a changing climate

There is an urgent need to anticipate and prepare for current and future challenges in a rapidly changing world. We also need to foresee new challenges to address issues of water scarcity (e.g., increasing desalination, use of treated wastewater in densely populated urban areas to meet water use demands), and aging infrastructure for many middle- and high-income countries constructed in the nineteenth and twentieth centuries. The impacts of climate change on the water cycle are direct and observable, such as more frequent droughts and floods, sea level rise, and ice/snow melt. These events will challenge drinking water quality and availability through direct and indirect mechanisms [ 21 ]. There is still very limited knowledge on how climate events will affect the quality of finished drinking water. In our special issue, Oliveras et al. conducts a new analysis on the impacts of drought and heavy rain surrogates on the quality of drinking water in Barcelona, Spain [ 22 ].

Chemical contamination of drinking water is widespread. Although our knowledge on chemical risks in drinking water is increasing, there are knowledge gaps that make a slow translation to public health protection. We hope this issue highlights, elevates, and motivates research on chemical exposures via drinking water.

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Donat-Vargas C, Kogevinas M, Benavente Y, Costas L, Campo E, Castaño-Vinyals G, et al. Lifetime exposure to brominated trihalomethanes in drinking water and swimming pool attendance are associated with chronic lymphocytic leukemia: a Multicase-Control Study in Spain (MCC-Spain). J Expo Sci Environ Epidemiol. 2024;34:47–57.

Friedman A, Boselli E, Ogneva-Himmelberger Y, Heiger-Bernays W, Brochu P, Burgess M, et al. Manganese in residential drinking water from a community-initiated case study in Massachusetts. J Expo Sci Environ Epidemiol. 2024;34:58–67.

Hefferon R, Goin DE, Sarnat JA, Nigra AE. Regional and racial/ethnic inequalities in public drinking water fluoride concentrations across the US. J Expo Sci Environ Epidemiol. 2024;34:68–76.

Spaur M, Glabonjat RA, Schilling K, Lombard MA, Galvez-Fernandez M, Lieberman-Cribbin W, et al. Contribution of arsenic and uranium in private wells and community water systems to urinary biomarkers in US adults: the strong heart study and the multi-ethnic study of atherosclerosis. J Expo Sci Environ Epidemiol. 2024;34:77–89.

Cserbik D, Casas M, Flores C, Paraian A, Haug LS, Rivas I, et al. Concentrations of per- and polyfluoroalkyl substances (PFAS) in paired tap water and blood samples during pregnancy. J Expo Sci Environ Epidemiol. 2024;34:90–6.

Kotlarz N, Guillette T, Critchley C, Collier D, Lea CS, McCord J, et al. Per- and polyfluoroalkyl ether acids in well water and blood serum from private well users residing by a fluorochemical facility near Fayetteville, North Carolina. J Expo Sci Environ Epidemiol. 2024;34:97–107.

Schullehner J, Cserbik D, Gago-Ferrero P, Lundqvist J, Nuckols JR. Integrating different tools and technologies to advance drinking water quality exposure assessments. J Expo Sci Environ Epidemiol. 2024;34:108–14.

Luben TJ, Shaffer RM, Kenyon E, Nembhard N, Weber KA, Nuckols J, et al. Comparison of Trihalomethane exposure assessment metrics in epidemiologic analyses of reproductive and developmental outcomes. J Expo Sci Environ Epidemiol. 2024;34:115–25.

Escher BI, Blanco J, Caixach J, Cserbik D, Farré MJ, Flores C, et al. In vitro bioassays for monitoring drinking water quality of tap water, domestic filtration and bottled water. J Expo Sci Environ Epidemiol. 2024;34:126–35.

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Dorevitch S, Geiger SD, Kelly W, Jacobs DE, Demirtas H. Repeated home drinking water sampling to improve detection of particulate lead spikes: a simulation study. J Expo Sci Environ Epidemiol. 2024;34:148–54.

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Deziel, N.C., Villanueva, C.M. Assessing exposure and health consequences of chemicals in drinking water in the 21st Century. J Expo Sci Environ Epidemiol 34 , 1–2 (2024). https://doi.org/10.1038/s41370-024-00639-0

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Published : 01 March 2024

Issue Date : January 2024

DOI : https://doi.org/10.1038/s41370-024-00639-0

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Environmental Science: Water Research & Technology

Unveiling microplastics pollution in alaskan water and snow.

While microplastics (MPs) are globally prevalent in marine environments, extending to the Arctic and sub-arctic regions, the extent and distribution of MPs in terrestrial waters, drinking water sources, and recreational water in these areas remain unknown. This field study establishes a baseline for MPs in surface water sources, including lakes, rivers, and creeks, as well as in snow across three geo-locations (i.e., Far North, Interior, and Southcentral) in Alaska. Results (mean ± SE) show that the highest MP counts exist in snow (681±44 L-1), followed by lakes (361±76 L-1), creeks (377±88 L-1), and rivers (352±98 L-1). The smallest MPs (i.e., 89.6±3 µm) also happened to have occurred in snow, followed by their larger sizes in lakes (153.4±13 µm), rivers (267.6±28 µm), and creeks (319.5±25 µm). The physical morphology of MPs varies widely. MP fragments are predominant (i.e., nearly 62-74%) in these sites, while MP fibers (nearly 13-21%), pellets (nearly 13-18%), and films (<6%) also exist in appreciable quantities. Geolocation-wise, the Far North, where MPs were collected from off-road locations, shows the highest MP counts (695±58 L-1), compared to Interior (473±64 L-1) and Southcentral (447±62 L-1) Alaska. Results also indicate that the occurrence of MPs in the source waters and snow decreases with increasing distance from the nearest coastlines and towns or communities. These baseline observations of MPs in terrestrial waters and precipitation across Alaska indicate MP pollution even in less-explored environments. This can be seen as a cause for concern with regard to MP exposure and risks in the region and beyond.

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S. Dev, D. Schwarz, M. Rashedin, M. I. Hasan, D. Kholodova, S. Billings, D. L. Barnes, N. Misarti, N. B. Saleh and S. Aggarwal, Environ. Sci.: Water Res. Technol. , 2024, Accepted Manuscript , DOI: 10.1039/D4EW00092G

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Why You Can Hear the Temperature of Water

A science video maker in China couldn’t find a good explanation for why hot and cold water sound different, so he did his own research and published it.

By Sam Kean

Most people are quite good at distinguishing between the sound of a hot liquid and the sound of a cold one being poured, even if they don’t realize it.

“Every time I give a talk and I say, ‘Surprisingly, adults can tell the difference between hot and cold water,’ people just go like this,” said Tanushree Agrawal, a psychologist who, during a video call, mimicked audience members shaking their heads no. But research she completed at the University of California at San Diego demonstrated that three-fourths of the participants in her experiments could in fact detect the difference.

You can try it yourself. Put on your headphones or listen closely to your computer or phone’s speaker and hit play on this audio recording.

Can You Hear the Temperature?

Could you tell which sound was hot and which was cold?

If you said the first one was cold, congratulations: You’re in Dr. Agrawal’s majority.

In general, cold water sounds brighter and splashier, while hot water sounds duller and frothier. But until recently no one really had evidence to explain the difference.

However, Xiaotian Bi, who earned a Ph.D. in chemical engineering last year from Tsinghua University in Beijing, offers a new explanation in a paper he and colleagues published in March on the arXiv website. It’s all about the size of the bubbles that form during pouring, he says, and this insight may have implications for how we enjoy everyday food and drink.

Dr. Bi’s paper has not yet been through peer review, and he acknowledges that much more research is needed. But Joshua Reiss, a professor of audio engineering at Queen Mary University of London, who has also studied the acoustics of hot and cold water, said he was “on the right track, for sure.”

Discussions of the varying sounds of hot and cold liquids usually point to differences in viscosity as the culprit. But Dr. Bi wasn’t satisfied with that reasoning. He produces and stars in his own popular science videos , and decided that the sounds water makes at different temperatures was a good topic . He poked around looking for published research on the subject and came away disappointed.

“None of them gave a precise explanation,” he said, adding that it was “an unsolved mystery.”

So Dr. Bi decided to do his own scientific investigation, which would inform his video. He used his expertise in fluid dynamics to explore the role played by bubbles, which actually create most of the sound we hear in moving water. You can observe this in waves, which glide along silently until they break, at which point they fall and trap air that produces noise as the bubbles resonate briefly within the water.

Previous research showed that larger air bubbles in liquids produce lower-frequency sounds. Dr. Bi also found that the acoustical spectrum of hot water has more low-frequency sounds than the spectrum of cold water. He wondered, then, whether pouring hot water into a container would trap larger bubbles than pouring cold would, and whether that might explain the difference in sounds.

His hunch proved correct. Dr. Bi purchased a container with a spigot to dispense water in a controlled fashion, first at 50 degrees Fahrenheit, then at 194 degrees. High-resolution videos and photographs revealed that hot water consistently produced bubbles 5 to 10 millimeters in size, while cold water produced bubbles around 1 to 2 millimeters.

(That’s why the cold water is on the left side of your screen in video above, and the hot water on the right)

In addition to offering an explanation of something that people hear, the research also provides insight into how we enjoy food and drink in general. Consider coffee.

Coffee tastes delicious when hot, but gunky and bitter when cold. That’s because aromatic flavor molecules jump off the surface of hot beverages more readily. And that link between flavor and temperature can produce a Pavlovian response in coffee drinkers.

This is consistent with an observation by Charles Spence, a psychologist who heads the Crossmodal Research Laboratory at Oxford and has won an Ig-Nobel Prize for research on the links between sound and taste when potato chips are consumed. In a 2021 paper, he wrote that “the sound of temperature likely helps to subtly set people’s aromatic flavor expectations,” even if unconsciously.

“Very often we taste what we predict,” he said. It’s all part of what he calls the hidden “sonic seasoning” of food and drinks.

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50 Years of Drinking Water Research

Published December 2, 2020

Harmful algal blooms are a major environmental problem in all 50 states. Some, but not all, types of HABs are overgrowths of toxin-producing algae in fresh or marine waters that can adversely affect human and animal health and local economies. Cyanobacteria (also known as blue-green algae) are a type of bacteria that exhibit characteristics of algae and can form these HABs. They often develop due to a combination of factors, such as excess nutrients, water temperature, and light availability.

In 2015, EPA began collaborating on the Cyanobacteria Assessment Network (CyAN) project with federal partners, including the National Aeronautics and Space Administration (NASA), the National Oceanic and Atmospheric Administration (NOAA), and the U.S. Geological Survey (USGS). The goal of the project is to provide federal, state, tribal, and local partners with the capability to detect and quantify algal blooms and related water quality using satellite data. This research collaboration led EPA scientists to develop the CyAN mobile application. The CyAN app, which was officially released to the public for download on Android devices in 2019, allows local and state water quality managers to easily assess satellite derived cyanobacteria biomass concentrations for over 2,000 of the largest lakes and reservoirs across the country. This easily accessible information can empower managers to make faster and better-informed management decisions related to cyanobacterial blooms. The team is currently developing a web-based version of the app, which will be compatible with most devices.

Another water challenge that EPA is addressing is the presence of per- and polyfluoroalkyl substances (PFAS) in drinking water resources. PFAS are a group of synthetic chemicals that have been used in a variety of industries around the globe since the 1940s. There is evidence to suggest that continued exposure to PFAS above certain levels can adversely affect human health.

To address concerns about the impact of PFAS chemicals in drinking water, EPA researchers have been conducting a variety of studies, including the development of standard analytical methods to detect the presence of PFAS in drinking water. These tested and validated methods are important resources to help government and private laboratories accurately and consistently measure PFAS in the environment so that they can make more informed decisions for their communities. In 2018, EPA released Method 537.1, which can be used to detect and quantify 18 PFAS chemicals in drinking water. The original Method 537 was published by EPA in 2009 and then revised in 2018 to include four additional PFAS, including HFPO-DA. In 2020, EPA made editorial updates to the method, and Version 2.0 of 537.1 is now available.  Researchers also helped develop the new validated Method 533, which can be used to accurately test for 11 additional PFAS. EPA and private laboratories can now use EPA methods 533 and 537.1to measure 29 PFAS chemicals in drinking water.

In addition, EPA is evaluating different drinking water treatment technologies that can remove certain PFAS from drinking water sources. This work has been added to the Drinking Water Treatability Database , an EPA resource that helps drinking water utilities, communities, states, and academics identify effective treatment processes for contaminants in drinking water. So far, EPA research has helped populate the database with 35 treatment processes and 123 regulated and unregulated contaminants. In a recent update in summer 2020, EPA added treatment and contaminant information about four new PFAS compounds. This update brings the total number of PFAS compounds in the database to 26, including PFOA and PFOS. Researchers have also added 20 new scientific references to the existing PFAS entries, which increases the depth of scientific knowledge available in the database.

For 50 years, EPA researchers have conducted research critical to protecting America’s drinking water. In the face of new challenges to drinking water resources and systems, EPA research has provided support to federal, state, tribal and local and partners through the development of methods to detect emerging contaminants and the creation of decision support tools like the CyAN app. As new challenges emerge, EPA remains committed to addressing threats to drinking water and public health.

Harmful Algal Blooms and Cyanobacteria Research

Per- and Polyfluoroalkyl Substances (PFAS) Research

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A Simple Technique for Removing Microplastics from Drinking Water Revealed by Research

A s microplastic fragments increasingly infiltrate our systems, largely through consumption of contaminated food and drink, scientists are seeking effective solutions to combat this issue.

Researchers from China’s Guangzhou Medical University and Jinan University have discovered a straightforward method to extract these tiny plastic pieces from water.

The team experimented with both softened water and mineral-rich hard tap water , introducing nanoplastics and microplastics (NMPs) to the samples, following which they boiled and subsequently filtered the mixture to remove the remaining solids.

In some experiments, this boiling and filtering process successfully eliminated up to 90 percent of the NMPs, depending on the nature of the water being treated. This technique is especially convenient since it can be carried out using common kitchen equipment.

The research team states, “This uncomplicated boiling strategy can ‘decontaminate’ NMPs from household tap water, potentially reducing human consumption of NMPs from drinking water,” in their published work .

Hard water, well-known for its tendency to develop limescale, or calcium carbonate , upon heating, showed greater NMP removal. The kettle’s familiar white deposits capture the microplastics as the calcium carbonate separates from the water during boiling.

The method proved effective even with softened water, which contains less calcium carbonate—approximately one-quarter of the NMPs were caught in this case. Trapped within a calcium carbonate layer, these plastic particles were then filtered out using a simple tool, such as a thin stainless steel mesh typical for tea-straining, according to the researchers.

Previous research has detected traces of various plastics like polystyrene and polyethylene in drinking water, leading to routine ingestion. To test their solution further, the researchers introduced an excess of nanoplastics, which subsequently saw a reduced presence.

As stated by the researchers, “Drinking boiled water appears to be a feasible long-term solution for diminishing worldwide NMP exposure,” despite the fact that this practice is not common globally and is mostly traditional in a few regions. [source]

The study aims to encourage the habit of water boiling prior to consumption, especially with microplastic contamination on the rise globally.

While the exact health implications of microplastic ingestion remain to be fully understood, there is increasing concern regarding its contribution to disturbance of gut microbiota and antibiotic resistance in humans.

The authors of this study express a need for further exploration into the role of boiled water in preventing the introduction of synthetic materials into our systems and mitigating the alarming impacts of microplastics.

“Our outcomes affirm a highly practical approach to minimize human NMP exposure and contribute to the groundwork for conducting broader investigations involving a much larger sample collection,” the team shares .

The research was detailed in the journal Environmental Science & Technology Letters .

FAQ Section:

Q: What are microplastics?

A: Microplastics are small plastic fragments typically less than five millimeters in size, resulting from the breakdown of larger plastic debris or from manufactured products such as microbeads in personal care items.

Q: How do microplastics end up in drinking water?

A: Microplastics enter water systems through various sources, including industrial runoff, waste water discharge, and the breakdown of larger plastics in the environment. They have been found in both tap and bottled water.

Q: Is boiling water an effective way to remove microplastics?

A: Yes, according to the study by researchers from Guangzhou Medical University and Jinan University, boiling water and then filtering it can remove a significant portion of microplastics from drinking water.

Q: Are there health risks associated with consuming microplastics?

A: The health effects of consuming microplastics are not yet fully understood, but there is concern that they can lead to changes in the gut microbiome and increased antibiotic resistance.

Q: How can the average person remove microplastics from their drinking water at home?

A: Based on the study, individuals can boil their tap water and use a household filter, such as one made of stainless steel mesh typically used for straining tea, to remove any trapped microplastics.

Conclusion:

Microplastic contamination in drinking water is a growing concern with potential health implications. However, the study from Guangzhou Medical University and Jinan University offers a practical solution for individuals looking to reduce their exposure to microplastics. By boiling and filtering their water, people can take an active step toward limiting their intake of these synthetic particles. As research continues, there is a collective hope for broader acceptance of this water purification practice and a deeper understanding of the impacts of microplastics on human health.