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Hydration: What You Need To Know

Importance of Water

It is difficult to argue against the importance of water to human life.  Water is necessary for every system in the human body to function.1  About 60-70% of a typical adult body's weight is water.2  Even though a minimum of 2 liters of water per day is recommended to maintain proper bodily functions, research shows that the vast majority of people in the United States simply do not drink enough water on a daily basis.3,4  

To put it plainly, dehydration occurs when a person loses body water at a faster rate than he or she replaces it.  When the body is without water for too long, chronic health disorders and their associated costs ensue.

Identifying Dehydration

The mnemonic DEHYDRATIONS was created by the Dehydration Council to help simplify screening for dehydration.  It goes as follows: "Drugs, e.g., diuretics, End of life, High fever, Yellow urine turns dark, Dizziness (orthostasis), Reduced oral intake, Axilla dry, Tachycardia, Incontinence (fear of), Oral problems/sippers, Neurological impairment (confusion), and Sunken eyes."5  While especially important in the elderly, looking for these signs can serve as a simple way to prevent long-term complications of dehydration for people of all ages.

How Much Water Should You Drink?

It is intuitive that drinking enough water to stay hydrated, under normal circumstances, will prevent dehydration from occurring.  The actual amount of water that should be consumed per day remains controversial because of the wide variety of differences and needs from person to person.  

A simple guide for people to remember is the 8x8 rule, that is, eight 8-ounce glasses of water per day.  The Adventist Health Study, a 6-year prospective cohort study of 8,280 men and 12,017 women without cardiovascular disease or diabetes at baseline, showed an association between high water intake (five or more 8-ounce glasses per day) and reduced risk of fatal coronary heart disease when compared with subjects who drank 2 or less glasses of water per day.6

The simplest and arguably the best approach to staying properly hydrated involves drinking enough water to prevent thirst and maintaining colorless to light yellow urine.

Things to Consider While Staying Hydrated

Not all drinks are created equally.  Caffeinated beverages such as tea and coffee and alcoholic beverages can act as diuretics, making it increasingly difficult to stay hydrated.  Also, much of our daily intake of water is through food, with fruits and vegetables containing the most water. 

It is important to note individual differences and needs as well.  Someone who weighs 200 lbs requires more water than someone who weighs 120 lbs, and males typically require more water than females.  Exercise, hot and dry environments, and high altitudes also warrant higher water intake.  Some medical conditions and medications may limit daily water recommendations.

Patients and consumers should consider consulting a physician before making any substantial dietary changes.


1.  Kleiner SM. Water: an essential but overlooked nutrient. J Am Diet Assoc. 1999;99(2):200-206.

2.  Pierson Jr RN, Wang J, Thornton J, Heymsfield S. The quality of the body cell mass--1996. Are we ready to measure it? Appl Radiat Isot. 1998;49(5-6):429.

3.  National Research Council Committee on Dietary Allowances, National Research Council (US). Food, and Nutrition Board. Recommended Dietary Allowances. Vol. 2941. National Academies, 1980.

4.  Kant AK, Graubard BI, Atchison EA. Intakes of plain water, moisture in foods and beverages, and total water in the adult US population—nutritional, meal pattern, and body weight correlates: National Health and Nutrition Examination Surveys 1999–2006. Am J Clin Nutr. 2009;90(3):655-663.

5.  Thomas DR, Cote TR, Lawhorne L, et al. Understanding clinical dehydration and its treatment. J Am Med Dir Assoc. 2008;9(5):292-301.

6.  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. May 1 2002;155(9):827-833.


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