20 Health Benefits of Drinking Water: Physical, Psychological and Nutritional

Drinking water (potable water) is derived from a surface, groundwater, precipitation, or recycled source that meets quality and safety standards to make it safe for human consumption.

Water is vital for life and makes up 50% (females) to 60% (males) of an adult’s body weight. Physiologically, water is the main constituent of cells, tissues, and organs. It supports numerous biological processes and ensures homeostatic functioning by acting as a building material, solvent, participant in enzymatic reactions, transporter of nutrients and wastes, thermoregulator, lubricant, and an essential component of blood.

Drinking water contains nutritionally beneficial minerals such as sodium, potassium, calcium, magnesium, and phosphate. People obtain the majority of their mineral needs from food, but water containing these minerals represents a useful supplement.

Sufficient, safe, acceptable, physically accessible, and affordable water for personal and domestic use is recognized by the United Nations as a fundamental human right. Lack of water as a fundamental resource is associated with emotional distress and negative mental health outcomes according to researchers at Arizona State University.

As a result, questions arise regarding how much water you should drink per day, the benefits of drinking water in the morning, the benefits of drinking water during dinner, the benefits of drinking a lot of water, and whether drinking a gallon of water per day may give the full benefits of hydration. In this article, we will evaluate the 20 health benefits of drinking water shown in this diagram

1. Improves Physical Performance

Physical performance, from a medical point of view, objectively measures whole body function related to mobility. It takes into account not only muscle strength, power, and endurance, but inputs from many other body organs and systems such as bones, balance, as well as various cardiovascular and neurologic aspects.

Substantial research has been conducted on the effects of hydration status on physical performance and related responses in occupational, military, and sports settings. This research has shown that dehydration or hypohydration provokes functional changes in cardiovascular, metabolic, and central nervous systems resulting in the impairment of physical performance. This impairment can be manifested by reduced endurance, increased fatigue, altered thermoregulatory capability, reduced motivation, and increased perceived effort.

A study from the American College of Sports Medicine showed that dehydration resulting in a loss of as little as 2% of body mass can be associated with a decline in physical performance. Another study conducted by researchers from the Department of Physiology of the Australian Institute of Sport found that low fluid intake in cyclers resulted in a relative performance impairment of 28.6%.

Since even minor percentages of water loss can have an impact on physical performance, drinking water and staying adequately hydrated during all types of physical activity is important for maintaining peak physical performance.

2. Increases Energy

Energy refers to the strength and vitality required for sustained physical or mental activity.

In the human body, energy is derived from dietary “fuel molecules”, namely carbohydrates, lipids, and proteins. These fuel molecules and their nutrient constituents (glucose, fatty acids, amino acids) subsequently undergo complex biochemical pathways to synthesize high-energy compounds, such as ATP, which functions as the main energy carrier in all cells. Drinking water is essential for all metabolic and biochemical pathways that are involved in the synthesis of high-energy compounds, which give all cells of your body fuel to function.

This diagram shows how water is used by the ATP/ADP cycle, which stores and releases energy in the body.

Lack of energy, as well as physical and mental fatigue, are the most common symptoms associated with dehydration. A study published in the British Journal of Nutrition found that fluid loss of 1.6% was detrimental to working memory and increased feelings of anxiety and fatigue.

3. Improves Brain Function

Water improves brain functions such as concentration and memory. The human brain controls all activities of our bodies. These include cognitive functions such as learning and remembering, motor functions, vision, and essential life functions such as breathing, heart rate, and even hunger.

Adequate hydration is important for optimal brain function. Studies have examined the effects of dehydration under different circumstances on brain functioning and have found that mild to moderate dehydration can alter important aspects of cognitive function such as concentration, alertness, memory, perceptual discrimination, arithmetic ability, visuomotor tracking, and psychomotor skills. As such, maintenance of adequate hydration by drinking water in hot climates and during vigorous exercise can help maintain optimal brain function.

A study conducted at Peking University entitled “Effects of Dehydration and Rehydration” followed 12 men who abstained from drinking water for 36 hours. Their mood and cognitive function tested before and after the 36 hours, with their average results coming out as seen in the charts below. Researchers concluded that dehydration had considerable negative effects on energy levels, attention, focus, and even short-term memory.

Studies have evaluated the effects of hydration on arousal and cognitive performance in young people and school-aged children. A study of school-aged children by the University of East London’s School of Psychology found that hydration improved visual attention of these children, while a study of young adults by the University of Bristol’s Department of Experimental Psychology found that water ingestion increased self-reported arousal and alertness.

4. Treats Constipation

Drinking water treats constipation that arises from insufficient fluid intake, especially when one has diarrhea or fever which promote dehydration. Constipation refers to difficult or infrequent bowel movements, hard stool, or a feeling that the rectum is not totally empty after a bowel movement.

Among numerous causes of constipation are dietary causes. The most important factors that promote constipation include reduced physical activity and inadequate intake of fibers, carbohydrates, and fluids. Constipation from these factors can be prevented by combining regular physical exercise with increased dietary fiber and water intake. The World Gastroenterology Organization’s guidelines on constipation include increased water intake as part of the treatment of constipation.

Constipation may result from illnesses such as diarrhea and fever, which promote dehydration and thus increase constipation. This type of secondary constipation is especially common among the very young and very old, for whom it is extra important to maintain good hydration to prevent constipation.

According to a study published in the European Journal of Nutrition, certain mineral waters rich in magnesium and sodium improves bowel movement frequency and consistency during constipation, especially in infants. The following mineral water brands profiled by the Fine Water Society contain high levels of magnesium or sodium.

Mineral Water Brand	Magnesium Content (mg/l)	Sodium Content (mg/l)
ROI (Slovenia)	1100	1100
Vichy Catalan (Spain)	6	1097
Gerolsteiner (Germany)	108	119
Pedras (Portugal)	24	577
ORO Luxury Water (North Macedonia)	310	40

5. Helps for Kidney Stones

Urinary stones are collections of mineral crystals (calcium, uric acid, struvite, cystine) that occur in the urinary system and can cause significant discomfort. Kidney stones, which originate in the kidneys, are the most common type.

Kidney stones are formed when waste materials in the blood crystallize and accumulate inside the kidneys, which may build up over time to create a hard stone-like mass. Dehydration is one of the factors associated with the formation of uric acid kidney stones. Increased fluid consumption is recommended for those individuals predisposed to the formation of uric acid stones.

Increased fluid intake increases the volume of urine going through the kidneys, thus diluting the concentration of minerals and making them less prone to crystallization and formation of stones. The American Urological Association, recommends that those who are prone to kidney stones should drink enough fluid to generate 2.5 liters (85 oz) of urine each day. On average, this equates to around 3 liters (100 oz) of liquids consumed every day.

6. Helps for Weight Loss

Drinking water helps weight loss by increasing feelings of being full, raising metabolism, and acting as a substitute for sugary drinks. Weight loss is defined as a reduction in total body weight induced by either voluntary or involuntary circumstances.

Increasing water consumption may help weight reduction by raising metabolism, which can increase the number of calories burned daily.

Consumption of water at least 30 minutes prior to meals has been shown to help weight loss, likely due in part to increased feelings of being full before eating. In one study, dieters who drank 16.9 ounces (0.5 liters) of water before meals lost 44% more weight over a period of 12 weeks than dieters who didn’t drink water before meals.

This figure lists just some of the ways that drinking water can help with weight loss.

Water contributes to weight loss by being an alternative to high-calorie beverages, which significantly contribute to obesity. A systematic review of the randomized clinical studies published in the Nutrición Hospitalaria journal in 2019 titled “Effect of water consumption on weight loss: a systematic review” showed that weight loss ranged from -0.4 kg to -8.8 kg with a mean percentage of weight loss of 5.15% after 12 weeks. The studies examined effects from replacing high-calorie beverages with water, increasing water intake, and drinking water before meals.

7. Prevents Hangovers

Hangovers are the unpleasant side effects of alcohol consumption and are manifested by headaches, fatigue, thirst, dizziness, nausea, and a loss of appetite.

The major cause of hangover symptoms is alcohol-induced dehydration. Alcohol has a strong diuretic effect, therefore it increases urine production, resulting in a loss of fluids and electrolytes required for normal functioning.

Although the best way to prevent a hangover is to not drink more than you know you can handle, drinking water helps. The National Health Service (NHS) of the United Kingdom recommends drinking water in between each alcoholic drink, as well as drinking at least 2 cups (16 oz) of water before going to sleep.

8. Prevents Dehydration

Dehydration refers to a significant loss of body water and electrolytes at a rate greater than the body's ability to restore it. Varying degrees of dehydration can be manifested by thirst, lethargy, altered sensorium, decreased cognition, dry mucosa, decreased urine output, tachycardia, hypotension, and shock.

Dehydration is caused by increased fluid loss (vomiting, diarrhea, excessive sweating, burns), decreased fluid intake (pharyngitis, other debilitating illnesses), or both. Preventing dehydration can be accomplished by drinking sufficient water daily, as generally guided by one’s own sense of thirst.

As a general volumetric guideline of how much fluid one should drink per day to avoid dehydration, the standard daily recommendations from the US National Academies of Sciences, Engineering, and Medicines is a good starting point. 3.7 liters (a little less than a gallon or 16 cups) of liquids a day for men and 2.7 liters (0.7 gallons or 11 cups) for women, which can then be adjusted based on factors like geographical location, temperature, activity levels, and age. For example, if a person is performing strenuous physical exercise during a hot summer day, they should increase their water intake beyond the minimum requirement in order to prevent dehydration.

This graphic illustrates some signs and symptoms of dehydration.

9. Carries Oxygen to Cells

The oxygen absorbed through the lungs from the surrounding air is bound to red blood cells which are “dissolved” in plasma, the liquid component of blood that allows circulation. Plasma is 90% water, therefore water acts as a carrier medium that allows for blood circulation, which is essential for the delivery of oxygen and nutrients to all cells.

Plasma normally makes up 55% of the body's total blood volume. Maintenance of plasma volume is performed by a complex system involving the renal and the neuroendocrine systems. Under normal circumstances, all that is needed to maintain the plasma volume necessary to remove waste products and transport oxygen and nutrients is to adhere to the recommended daily water intake requirements and to let our bodies do the rest.

This graphic shows the components of blood and the high percentage of water in plasma.

10. Improves Digestion

Digestion is the process through which insoluble dietary macronutrients such as fats, carbohydrates, and proteins are mechanically and enzymatically broken down into micronutrients that can cross the intestinal epithelium and enter the bloodstream for use in the body.

Digestion begins in the mouth with chewing and ends in the small intestine. As food moves through the gastrointestinal tract, it mixes with digestive fluids (saliva, stomach acid, pancreatic juice, bile acids) causing big molecules of food to break down into smaller ones that are absorbed.

Water is required for proper digestive functioning. It provides lubrication of mucous membranes in the gastrointestinal tract, helps in breaking down meals in conjunction with gastric acid and enzymes, promotes gastric emptying, promotes intestinal motility, and assists in the control of bowel movements.

Dehydration and hypohydration promote poor digestive health and are associated with delayed digestion, bloating gastric acid reflux, and constipation. For example, researchers from the Department of Gastroenterology at the University Hospital Maastricht found that dehydration leads to delayed gastric emptying. Adhering to the recommended daily liquid intake of 2.7 liters for women and 3.7 liters for men (adjust to personal circumstances) will help ensure healthy digestion.

11. Regulates Body Temperature

Body temperature is a measure of the human body's capacity to regulate internal heat. Water is essential for regulating body temperature, as it limits changes in body temperature in a warm or cold environment due to its large heat capacity.

This is primarily seen during a rise in body temperatures due to fever or when the ambient temperature is higher than body temperature. Under these conditions sweating is elicited, and as sweat evaporates it allows for the dissipation of excess heat from the body. A state of adequate hydration is crucial to the body's temperature-regulating process, especially during vigorous physical activity, high ambient temperatures, or fever.

The following image compares the amount of heat lost by the body by various means.

Excessive sweating can lead to hypohydration and dehydration if the lost water volume is not replaced. According to the review article “Water, hydration, and health” in Nutrition Reviews, during a state of dehydration when there is reduced plasma volume and increased plasma osmolality, sweat output becomes insufficient and increases in core temperature cannot be offset which can lead to conditions such as heat exhaustion and heatstroke. Drinking water is important to prevent such conditions.

12. Provides Electrolytes

Electrolytes are ionized or ionizable constituents of a living cell, blood, or other organic matter and are essential for basic life functioning. In the human body, the most common electrolytes are sodium, potassium, chloride as well as magnesium, calcium, phosphate, and bicarbonates.

This figure shows the uses of electrolytes needed by the body.

Water can contain minerals and electrolytes, however, their quantities in different water supplies vary greatly. They may be present in drinking water sources naturally as is the case with mineral waters that come from underground sources with stable concentrations, or they can be intentionally added. As such, drinking water can be an important source of electrolytes for individuals.

13. Protects Organ Tissue

An organ is a group of tissues, which are themselves composed of groups of cells, that work together to perform the overall function of the organ.

In the human body, approximately 66% of the total body water (TBW) is located in the intracellular fluid compartment, with 90% of this intracellular fluid being localized inside the cells of high water density organs such as the brain, lungs, kidney, liver, muscles, and skin; while the remaining 10% is found inside of red blood cells.

This figure shows the percentage of water in important body organs.

 

The water inside these cells helps maintain their shape and acts as a shock absorber, preventing injury when cells are put under stress. The shock-absorbing properties of water are especially important for the musculoskeletal system (joints) during walking or running, as well as for the brain and spinal cord, which are surrounded by a protective layer of fluid. Drinking sufficient water ensures the body can maintain the proper amount of water within the organs.

14. Flushes Bacteria from Bladder

Bacteria in the bladder can result in urinary tract infections (UTIs) which are infections of the bladder (cystitis) and associated structures (e.g. urethra, prostate). UTIs are characterized by painful urination, frequent urination, hesitancy, urgency, and sometimes even blood in the urine. UTIs are among some of the most common infections, especially in women, with 40% to 60% having a UTI at least once in their lives.

There are numerous factors that increase the risk of developing a UTI. Among these risk factors are those conditions that prevent complete emptying of the bladder and/or result in the stagnation of urinary flow, as urine is an ideal medium that allows for bacterial growth.

Staying adequately hydrated by increasing fluid intake can help decrease the incidence of UTIs and is even advised during active UTIs. A study published in the Canadian Journal of Infectious Disease and Medical Microbiology found that frequent urination and high urinary volumes can decrease the risk of UTIs by “flushing” possible pathogens out of the urinary tracts.

This chart shows how Urinary Tract Infections were reduced by higher water intake.

15. Improves Immune System

The immune system is a complex collection of cells, tissues, and molecules that work together to help the body resist and fight infections.

Our immune system is highly dependent on the circulatory system for the delivery and transport of nutrients and infection-fighting white blood cells throughout the body, as well as on the lymphatic system for the removal of toxins and foreign pathogens. Hydration is a key component for both the circulatory and lymphatic systems, as they are made of mostly water. Consuming the daily recommended quantity of water ensures that our immune system functions correctly.

A study from the Hirosaki University Graduate School of Medicine found that dehydration may even lead to immunosuppression through decreased neutrophil function, which is a common type of white blood cell that is involved in antigen recognition, engulfment of foreign pathogens, and production of bactericidal substances.

16. Helps against Depression

According to the American Psychiatric Association’s Diagnostic Statistical Manual of Mental Disorders, depression is a mood disorder that causes persistent feelings of sadness and loss of interest.

It is believed that drinking water is good for one's mental health as it promotes brain function by facilitating signaling routes and nutrition supply to the brain, removing toxins and inflammatory indicators, and providing energy sources for the brain.

A study from the School of Nutrition and Food Science at the Isfahan University of Medical Sciences found that drinking water may be associated with decreased risk of depression and other psychological disorders, as consuming less than 2 glasses per day was associated with 73% and 54% increases in the risk of depression in men and women respectively. Although the study suggests that the effects water consumption has on the risk of depression are multifactorial and not well established.

In this podcast, Ph.D. nutritionist Susan Taylor discusses the way drinking water impacts mood.

17. Helps Prevent and Treat Headaches

A headache is defined as discomfort or pain in any part of the head that is related to irritation and/or inflammation of intracranial or extracranial structures with pain receptors.

Dehydration and hypohydration have long been known to be associated with headaches, and are clinically categorized under “Headache attributed to other disorder of hemostasis”. Despite this, the link between them and the pathophysiologic mechanism still remains unknown. For example, the one proposed mechanism (Monro-Kelli doctrine) suggests that bodily water deficit can result in dural venous stretching and thereby provoke a headache.

One study examined the association between water intake and migraines in women and found that women who drank more water (approximately 2 liters/day) had reduced severity, duration, and frequency of migraine attacks as well as reduced attack-associated disability compared to those women who drank less.

Headaches have been associated with water deprivation as seen during religious, cultural, or personal practices of fasting. According to a study by the National Hospital for Neurology and Neurosurgery in the United Kingdom, these “water deprivation headaches” usually occur within 8-16 hours of initiation of fasting and can be relieved within minutes of consuming fluids.

“Water deprivation headaches” can be treated simply by drinking water. Drinking water can be useful in migraine prevention. A randomized trial on the effects of regular water intake in patients with recurrent headaches by the University of Maastricht found that long-term management of migraines may benefit from adequate fluid intake (greater than 2 liters per day) in addition to other lifestyle modifications.

These are some natural remedies to assist with relieving headaches, including drinking water.

18. Improves Productivity

Productivity refers to the ratio of outputs over inputs. It measures how efficiently production inputs, such as knowledge and labor, are used by an individual to produce a given level of output or goal.

Physical and cognitive productivity in a variety of occupational settings is often measured by occupational health and safety researchers. A few studies have assessed the effects of dehydration on productivity under high heat stress occupational settings. One such study by Robert W. Kenefick published in the Journal of the American College of Nutrition found that dehydration can adversely affect worker productivity, safety, and morale.

Legislative bodies in North America such as the Occupational Safety and Health Administration (OSHA) and the American Conference of Governmental Industrial Hygienists (ACGIH) recommend replacing fluids frequently when exposed to heat stress, such as one cup (250 ml) every 20 minutes when working in warm environments.

19. Improves Muscle Growth

Muscle growth occurs when individual muscle fibers grow in size or hypertrophy. The relationship between water intake and muscle growth is not well understood, but at least one study suggests there is a link.

The study from the Carlos III Health Institute in Spain that reviewed the role of water homeostasis in muscle function and frailty suggests that muscle cell dehydration has negative impacts on intracellular protein structure and function of myocytes and leads to their damage. They suggest that water volume inside muscle cells may act as a metabolic signal, with cell shrinkage due to dehydration acting as a catabolic (breakdown) signal, and cell swelling due to hyperhydration acting as an anabolic (building) signal. Suggesting that staying hydrated may improve muscle growth by acting as a signal that triggers muscle cell growth.

20. Protects Joints

Joints are defined as a structure in the human body at which two parts of the skeleton are fitted together. There are three different kinds of joints depending on the type of tissue they are composed of: fibrous, cartilaginous, and synovial.

Synovial joints are considered the main functional joints of the body and include freely mobile joints such as the knee, hip, and elbow. These joints are characterized by a joint cavity that contains fibrous connective tissue as well as synovial fluid, which functions as lubrication to reduce friction during movement. Adequate hydration is important to produce synovial fluid and protect joints.

The following illustrations show the water components in synovial joints and intervertebral discs.

Additionally, joints and intervertebral discs of the spine contain cartilage which contains around 80 percent water. It has been suggested that long-term dehydration can reduce the cartilage’s shock-absorbing ability, leading to joint damage and pain.

How Much Water Should You Drink a Day?

You should drink 3.7 liters (a little less than a gallon or 16 cups) of water a day for men and 2.7 liters (0.7 gallons or 11 cups) for women according to a study conducted by the US National Academies of Sciences, Engineering, and Medicine. However, when asking "how much water should you drink a day?" the answer can vary significantly depending on factors like geographical location, temperature, activity levels, and age. Your body may need more water than the above-recommended amount, depending on various external factors.

To account for body weight and exercise, physical therapist and clinical supervisor Jennifer Stone suggests two other very basic formulas, displayed below, for determining how much water to drink per day.

What Are the Benefits of Drinking Water in the Morning?

The benefits of drinking water in the morning are listed below.

1. Drinking water in the morning facilitates weight loss.
2. Cognition, memory, attention, and mood are improved with morning water drinking.
3. Skin density is improved by drinking water in the morning.
4. Drinking water in the morning helps prevent kidney stones.

Drinking two to three 250ml glasses of water in the morning is often advised by doctors for better health.

Should You Drink Water Before Sleep?

You should drink a bit of water before sleeping. Whether you should drink water before sleep depends on your level of hydration and sleep habits, with the general answer being to stay hydrated throughout the day and then to drink a bit of water before sleeping.

Drinking water prior to sleep helps prevent overnight dehydration during hot temperatures and may facilitate sleep by inducing a drop in core body temperature. It also helps lessen hangover effects.

However, drinking water before sleep may increase the frequency of nighttime awakenings and urination. Frequent nighttime awakenings disrupt an individual's sleep cycle and as a result, are associated with decreased productivity, injuries, and even depression.

Should You Drink Water Before Dinner?

You should drink water before dinner if you wish to decrease your calorie intake by feeling more full before eating. Certain small studies have suggested that water consumption prior to and during meals may increase satiety and cause changes in the subjective sensations of satiety associated with reduced energy intake, which is thought to lead to weight loss. One study from the Department of Human Nutrition, Foods and Exercise at Virginia Tech did indeed find that water consumption increased weight loss, though this was when combined with a hypocaloric diet.

Should You Drink Water during Dinner?

You should drink water during dinner to replace sugar-sweetened beverage alternatives. Doing so is beneficial to health, according to the Dietary Guidelines for Americans by the US Department of Health and Human Services and the US Department of Agriculture.

What Are the Benefits of Drinking a Gallon of Water Every Day?

Drinking a gallon of water a day benefits include improved physical performance, increased energy, improved digestion, and improved productivity.

A gallon of water is equivalent to 3.785 liters, which is roughly equivalent to the 3.7 liters of liquids a day men should drink and slightly more than the 2.7 liters (0.7 gallons) of water a day recommended for women. Your specific water intake needs vary depending on factors like geographical location, temperature, activity levels, and age.

What Is the Difference of Luxury Drinking Waters?

The difference of luxury drinking waters from ordinary drinking water depends on the brand but can include exotic sources, high-end (almost always glass) packaging, unique mineral components, and unique origin stories. This is a list of luxury bottled waters and the factors that make them unique. 

Luxury Water Brand	Country of Origin	Unique Factors
Aur’a Natural Gold Water	Romania	Naturally enriched with colloidal gold and silver
Svalbarði Polar Iceberg Water	Svalbard, Norway	World’s northernmost bottled water, rare iceberg source, carbon negative, award-winning packaging
Nevas Water	Germany	Champagne replacement in an appropriate bottle, unique cuvée of two different spring water sources
Fillico Jewelry Water	Japan	Over-the-top crystal-encrusted bottles
APSU Origin Water	Chile	Rare glacial meltwater source from Patagonian wilderness

How to Avoid Dehydration?

Dehydration refers to a significant loss of body water and electrolytes at a rate greater than the body's ability to restore it. Varying degrees of dehydration can be manifested by thirst, lethargy, altered sensorium, decreased cognition, dry mucosa, decreased urine output, tachycardia, hypotension, and shock.

The best way to avoid dehydration is by adhering to the daily water intake requirements and adjusting them based on your individual circumstances. Ways to ensure you drink enough water and avoid the effects of dehydration include having a glass of water when you wake up in the morning, carrying a water bottle with you if you are away from home for long periods of time, avoiding the mid-day sun, limiting physical activity when the ambient temperature outside is very high, and scheduling outdoor activities during the morning or evening when it is relatively cooler outside.

This graphic shows some of the best ways to avoid dehydration.

What Are the Symptoms of Drinking Too Much Water?

The most prominent of the 9 signs you're drinking too much water are nausea, drowsiness, and confusion. Simply ceasing to drink water can usually quickly treat these symptoms. In rare instances of severe water intoxication, seizures, organ failure, and even death can result. One should focus on a healthy daily water intake that in which you are neither going through the day thirsty or urinating excessively.