Psychology Department

Health Psychology Home Page

Papers written by students providing scientific reviews of topics related to health and well being

Search HomeWeight LossAlternative Therapy | Supplements | Eating Disorders | Fitness | Links | Self-Assessment | About this Page |


Drinking Eight Glasses of Water a Day




Stacey Schrecengost

Health Psychology 115A

November 13, 1998


Table of Contents


Part One: Liquid Effects……………….……………........3

Part Two: Support and Claims………………………........4

Part Three: Who Should Be Drinking……..……….…......5

Part Four: Why People Don’t Drink………………….......6

Part Five: Getting In the Habit of Drinking…….……........7

Part Six: The Ins and Outs of Water in the Human Body....7

Part Seven: Thirsty Implications...........................................8


Summary of Thirst..................................................................9

Works Cited............................................................................10




"If you drink all of that water you will float away." "I’m not thirsty." "I’ll just have to go to the bathroom if I drink all of that liquid." "Water doesn’t do anything for me, I will just grab a coke." Everyone has either made or been present when a comment like the ones above was made. Recently though, the trend is that nearly everyone carries a water bottle with them and sips all day long. But what does water really do for the body? Is it essential that people gulp down the prescribed eight glasses of water for optimal health and performance? Substantial information now points to evidence that water is beneficial to your health.

Hydration with water and other water-based liquids is critical for survival and functioning of the body’s organs. Water is 60% of the total human body composition. Water is involved in the function of temperature regulation, elimination of waste and secretion, digestion, and is 80% of blood composition. Deborah Boardly, assistant professor of health promotion and human performance at the University of Ohio in Toledo says, "I truly believe that dehydration (insufficient body fluids) may be the number one nutrition problem for athletes—and, possibly, people in general." Boardly goes on to say, "Today we have all these concerns about everything we should and shouldn’t eat—and yet here is this absolutely fundamental substance and it is grossly overlooked."(

Scientist, doctors, and businesses alike are making claims about water. Scientists are trying to formulate data and construct studies that prove the effectiveness of using water on a daily basis. Doctors are instructing their patients to use water to help cure minor ailments and boost the overall condition of the immune system. Businesses and industries are concerned with the economic implications of the water trend. The businesses can manipulate customers into purchasing many products and make high profits. Many differing claims are being made about the effects of water by varying groups to use for their own purposes.

Despite the strong claims being made by many parties, some individuals are still not drinking water. The excuses for not drinking water vary in such ways as; forgetting and water being inaccessible. Much of the American public, however, is uninformed about the benefits and the consequences on health of not drinking water. Also, many Americans think that any liquid qualifies as hydration. Confusion exists about what is the best liquid to drink and whether purified or higher quality is better. With the misunderstandings and unconcerned public, America is often dehydrated.

Dehydration is a problem that can be fixed easily through self-awareness and a conscious effort to drink. Many techniques exist to help facilitate and encourage water consumption: making drinking water a habit; keeping a liquid journal; and making water more appealing. Although the topic of water consumption and drinking eight glasses of water appears to be such a simple element of health, it is key to effective body function, and optimal health.


Part One: Liquid Effects

Part One: Liquid Effects

Liquid is continually present and functioning in our bodies. The process is like a heart beating: we do not think about the water in our bodies unless we have an insufficient amount and we feel thirsty. "According to health professionals, most people live at a level of mild dehydration, especially during the hot summer months. However, hydration is at least as important as nutrition for maintaining good health."(

Water consumption is crucial to health. In the worst case, Deborah Boardly says, "dehydration can become a literal life-or-death matter. But experts say that far too many individuals fail to recognize the simple but vital role water plays in just plain feeling good." Water has the power to make one feel healthy, revived, and balanced. Water is not the cure-all for every disease but can have an impact. To prove that water will have an impact on the body, go a day without drinking. No one in his or her right mind would follow this advice because of human instinct. The body’s systems would deteriorate and a person would feel run down. Water as it enters the body has several functions. According to Chimes, a Calvin College newsletter, "The adult human body is about sixty percent water. Blood is ninety percent water, muscles are seventy-five percent water and bone is twenty-five percent water." ( With water being one of the main structures in the body, water intake helps to balance and regulate almost every system. Water is involved in temperature regulation, digesting and then excreting waste. Blood is water based; water lubricates internally, helps in chemical break down of the body’s other nutrients, and cushions organs and joints. "Water is considered a macro-nutrient, one of the basic building blocks of life… Water not only gives substance to your body’s cells; it’s vital to their utilization of other nutrients."( Water is the oil that keeps the human body running smoothly.

Part Two: Claims

Part Two: Support and Claims

On the television, in magazines, from the doctor’s advice, and from scientific studies, we are bombarded with information about water. Everywhere one turns there is a picture or someone talking about the water. People are trying to answer the question, "What can water do for my health and well-being."

Water intake is essential for survival, and doctors try to make sure that their patients drink enough liquids to stay healthy. Doctors have seen how water can help facilitate the healing process. They are looking out for the well-being of the patient in prescribing water use. When an individual gets sick one of the first questions that a doctor or nurse will make is, "Have you been drinking your liquids? If not you should really be increasing your water intake, especially when you are sick like this." In a article called Water is Cheap Insurance by Tim Neunschwander fitness director of the North End Family Practice, he says, "One of the easiest ways to help the body function optimally and remain disease-free is to keep it well hydrated. In drinking sufficient water throughout each day, we assist our body’s ability to flush toxins and metabolic waste."(

Entrepreneurs and businesses have also caught on to the craze of water and are trying to bottle the profits. The claims that are made by the business sector are made with the intent of selling their product. In many cases false information or embellished data is given to increase sales. If Pure water brand filters can prove that drinking water is a sure cure for many common health problems, sales will skyrocket. Claims made by people making a profit from water should be investigated.

Scientists are currently conducting studies and collecting data on the effects of hydration. Boardly says that recently, "Researchers have done studies that show some evidence of people who have headaches or fatigue, and all they really need is water." Researchers are looking for the long term effects of drinking water in the overall scheme of body function. But data, too, can be manipulated for personal use.

Everyone should be consuming some amount of water for their body to function correctly, but there are now people claiming that the amount of water one needs is questionable. The eight glasses of water advice is a good "one-size-fits all" indicator of how much one should drink but there are other factors.

The factors include; "Issues ranging from age and body size, overall diet and specific foods and beverages consumed, medical conditions (including drug use), activity levels, and average temperatures…" ( html) Based upon these factors one should consume a varying amount of water.



Part Three: Who Should Be Drinking?



"So let man consider of what he was created; he was created of gushing water…"

~Qur’an. The Night-Star, 86:5-7


Part Three: Who Should Be Drinking?

Every human being should be consuming water or some other type of liquid. Certain groups require more liquid intake, though. Dr. Kenneth G. Berge of the Mayo clinic says, "Humans normally lose about ten cups of fluid a day in sweat, urine, exhaled air and bowel movements. What is lost must be replaced to maintain a fluid balance." "Dehydration poses a particular health risk for the very young and the very old." Other situations in which water consumption should be increased are people with kidney stones or when environmental conditions are changed like high altitude or hot dry weather. (



Part Four: Why People Don’t Drink


 Water, water every where,

Nor any drop to drink.

~S.T. Coleridge, The Ancient Mariner



Part Four: Why People Don’t Drink

People often wait to drink until they are thirsty. At the point when the body’s mechanism for thirst turns on, the body is already dehydrated. So why don’t people drink water? In a study done by the Nutrition Information Center at the New York Hospital and the International Bottled Water Association, "people have good excuses for not drinking water: not enough time (27 percent); don’t feel thirsty (11 percent); don’t like the taste of water (8 percent); forget to drink it (7 percent). Researcher Barbra Levine suspects that they really are, ‘concerned about being able to get to the bathroom’"(

Besides the excuses for not drinking water, people are confused about comparative the same hydration values of other liquids. Levine says, "Those people who drink iced tea all day or a lot of beer at the ballgame are not doing themselves any good…people tend to underreport how much alcohol they’re consuming." Caffeine containing beverages and alcohol are diuretics, which means that they cause urination. When talking about drinking diuretics Levine says, "The vast majority aren’t drinking enough water to begin with and to make matters worse, many don’t realize that beverages containing alcohol and caffeine actually rob the body of water." ( People just assume that their body is hydrated with the coke that they drank for lunch and the beer from after work. The key to feeling the effects of water is to begin drinking and to drink continually throughout the day.



Part Five: How to Get In The Habit of Drinking

Part Five: How to Get In The Habit of Drinking

Drinking water to maintain high fluid levels in the body is crucial but some people just cannot seem to get into the habit of drinking. Different doctors and nutritionists give advice on how to start, continue drinking water and get the most out of the liquid that is drunk. With the help of a few tips, water can be properly utilized on a daily basis.

To get at the heart of the reason people don’t drink water, going back to people’s excuses is required. The most popular excuse was that people did not have time to drink water. With education about the functions that water plays a part in and its positive effects people would probably make an effort to drink more. It takes only seconds to take a sip of water, but the effects of water are long-term. The second excuse that people just, "don’t feel thirsty," is easy to knock down because, if a person waits till they feel thirsty they are already dehydrated. Deborah Boardly says, "waiting to drink until you’re parched is a big mistake…that means your blood level of water is so low that you’re now drawing water from your salivary glands, which cues thirst." The third major reason that people do not drink waster is that it does not taste good, this is easy to cure. Tim Neuenschwander suggests: trying a sports drink; adding a lemon wedge or mint tea-bag to a cup of water; and making an effort to consume watery fruits.( The final excuse of forgetting to drink is very simple to solve. One should get into the habit of carrying a water bottle everywhere with them. The water bottle becomes like a purse or a safety blanket. It is something that is always there and you don’t lose it. Other advice is to, "get into the habit of hydration by starting with a glass of water with every meal, and then work in a cup between meals."( Common sense and an effort to up water consumption will also make it easier to break into the habit.




Part Number Six: The Ins and Outs of Water in the Human Body

Part Number Six: The Ins and Outs of Water in the Human Body


The volume of fluid stays within a very narrow range in the human body. It is crucial to human life that this range is kept constant. Although, in infancy the water content of the body is higher and the body water in the elderly tends to stay at low levels, the system of keeping the body fluid volume constant is a complex one. There are several methods to input water into a human system. The main way to gain water is through drinking water. Another way humans gain water is from the foods they eat. The ways in which water is outputted are urination, defecation, salivation, sweating, bleeding, and by breathing out air.

When water enters, the body it is divided into two compartments; the extracellular and the intracellular areas of the body. The intracellular compartments of the body are the areas between the cells and the extracellular compartments are the areas outside the cells. Two-thirds of the water entering the body will remain intercellular and the remaining one-third becomes a key component of plasma in the body.

Central to water regulation and conservation are the kidneys which regulate the intake and output of water in humans. The kidneys’ main job is to form urine from blood. The blood composition remains as constant as possible throughout this process and only a selective amount of water, depending water levels at the time is processed. For example, when a person is drinking more than the prescribed eight glasses of water, he or she will just urinate the excess fluids out. The kidney also excretes hormones from the endocrine system that directly effects fluid balance.



Part Seven: Thirsty Implications

Part Seven: Thirsty Implications


The benefits of drinking water were determined in the previous sections but the questions are, do people require water, and what controls the desires to drink water? Thirst can be defined as, "subjective sensation aroused by a lack of water…/Associated with the sensation of thirst is the desire to drink water, and usually thirsty subjects report a dry feeling in the mouth and find that water tastes pleasant"(Rolls and Rolls, 1982). Thirst is the first signal clue of the body that one is dehydrated.

The onset of thirst begins when the body is dehydrated and lacking fluid. The body’s fluid compartments are not in homeostasis and the resulting reaction is thirst. The resulting sensation that one should drink is the behavioral response to lack of water (Cannon, 1947). The body then uses signals such a dry mouth, to influence the individual to drink water.

One of the major cues to drink fluids, a dry mouth, has traditionally been a focus of the subject of dehydration. When speaking of the early physiologist Cannon's theory on dry mouth, researchers and authors, B.J. and E.T. Rolls state, "[t]here is no doubt that salivary flow correlates well with the need for water" (p.23). Early experiments done by A.V. Wolf support the connection between thirst and a dry mouth sensation. Wolf desensitized the mouths of both humans and dogs with cocaine. The result was a cessation of thirst.

Thirst, besides being initiated just in the mouth and throat, has broader origins. According to Penn State physiology professor, Elsworth Buskirk and New York at Cortland Physical Education professor Susan Puhl, "[t]hirst and drinking are controlled by integration of signals from osmoreceptors, and volume receptors, as well as palatability of fluid available."(p. 12). Osmoreceptors are "specialized cells in the hypothalamic region that somehow transduce change in their osmotic state to neuronal and hormonal stimuli…" (Elsworth & Puhl, 1997) (see figure 1.1 for cited information about the effect of certain osmoreceptors). The osmoreceptors control thirst in intercellular dehydration. In extracellular dehydration cardiac receptors control fluid volume because the major fluid of the extracellular compartment is plasma.

The palatability of a fluid to be ingested also has an impact on hydration levels. If a fluid is more palatable, there will be an increase in consumption of the fluid and therefore an increased hydration level. One of the easiest ways to induce drinking is to add a sweet flavoring, because a sweet taste appeals to individuals' taste buds. In a study done by B.J. Rolls and other researchers using rats, they concluded that by adding saccharin to water rats would drink much more if it were sweetened water. On the other side of this, bitter tasting fluids inhibit consumption because they are not appealing. Rolls concludes, "We have just seen that giving liquid a pleasant taste significantly increases fluid consumption" (84).


[FrontPage HTML Markup Component][FrontPage HTML Markup Component]Conclusion

The crystal clear nutrient water, is often overlooked but should not be forgotten. Water is the basis of human structure and life. "It is only second to oxygen," in survival. Water is an essential element of a healthy and efficient life. The positive effects water has on the body are never ending. Because water makes up so much of the body’s composition, it is essential that hydration or fluid balance are kept.

The positive effects of water, in combination with the need to stay hydrated, have brought many claims and support for the use of water. Doctors are using liquid to help heal their patients. Businesses are making a profit off of the water madness and scientists are busy collecting data to prove the positive effects of water. Credibility and motives must be weighed when deciding what to believe about water.

Even if some claims are blown out of proportion, water should be consumed by everyone on a daily basis. Specifically older adults and children should make a deliberate effort to consume large amounts of water. People don’t drink water for varied reasons but each rationalization can be refuted. Water is a powerful tool and should be used by all people. When exercised in the right ways, it can be used to attain health and well-being. Researchers who have studied the effects of water use have shown us that a healthier life is within the grasp of each individual. When one embraces water, consumption health is sure to follow. So don’t forget about water; getting in the habit of drinking water is simple, and the benefits far outweigh the minute effort needed.



Summary of Thirst

The brain and the overwhelming sensation of thirst control dehydration in the body. When water enters the body it goes through a number of different transformations but eventually is divided into two compartments; the extracellular or the intracellular compartment. While in the compartments, osmoreceptors monitor cellular dehydration with stimuli and receptors and the extracellular compartment is monitored by cardiac receptors. For proper function, the water volume in the compartments is to be kept at homeostasis. When a lack of water is present, stimuli and hormones are released to encourage fluid intake. The human body has a complex system of balances and processes which help to ensure that through thirst and conservation, the body will stay hydrated and function most efficiently.



Works Cited

Buskirk, E.., & Puhl, S. (Eds.). (1997). Body Fluid Balance. New York: CRC Press.

Cannon, W.B. (1947). The Wisdom of the Body. London: Kegan Paul,Trench, Trubner & Co.

Rolls, B.J., &Rolls, E.T. (1982). Thirst. Great Britain: Cambridge University Press.

Weldy, J. W. (1997). A programmed presentation. Body Fluids and Electrolytes. (7th ed.). St. Louis: Moseby..



 We never know the worth of water till the well is dry.

~Thomas Fuller, Gnomologia, 5451

Table 1.1

Intracellular Osmoreceptors

Arginine vasopressin (AVP): When secreted, drinking stimulated.

Angiotensin II (AII): When released stimulation of AVP occurs.

Brain Natriuretic Peptide (BNP): Suppresses salt and water intake.

Atrial Naturiuretic Peptide (ANP): Blocks all induced drinking.

--(Buskirk & Puhl, 1997).

Created By: Stacey Schrecengost

Email To:





Psychology Department

The Health Psychology Home Page is produced and maintained by David Schlundt, PhD.

Vanderbilt Homepage | Introduction to Vanderbilt | Admissions | Colleges & Schools | Research Centers | News & Media Information | People at Vanderbilt | Libraries | Administrative Departments | Medical 

  Return to the Health Psychology Home Page
  Send E-mail comments or questions to Dr. Schlundt


Search: Vanderbilt University
the Internet
  Help  Advanced
Tip: You can refine your last query by searching only the results by clicking on the tab above the search box
Having Trouble Reading this Page?  Download Microsoft Internet Explorer.