The Cleveland Clinic Health Information Center
The Cleveland Clinic


The Benefits of Water

Almost everyone knows that you should drink eight glasses of water a day. But is it really necessary?

"Absolutely," says Cleveland Clinic nutritionist Andrea Dunn. "Almost every cell in your body needs water to function properly. Many of the patients I see don’t drink enough water. They aren’t dehydrated, but they aren’t drinking as much water as they should -- especially considering how much your body needs."

The human body, which is made up of between 55 and 75 percent water (lean people have more water in their bodies because muscle holds more water than fat), is in need of constant water replenishment.

Consider this: Your lungs expel between two and four cups of water each day through normal breathing - even more on a cold day. If your feet sweat, there goes another cup of water. If you make half a dozen trips to the bathroom during the day, that's six cups of water. If you perspire, you expel about two cups of water (which doesn’t include exercise-induced perspiration).

Ms. Dunn points out that a person would have to lose 10 percent of her body weight in fluids to be considered dehydrated, but as little as two percent can affect athletic performance, cause tiredness and dull critical thinking abilities. Adequate water consumption can help lessen the chance of kidney stones, keep joints lubricated, prevent and lessen the severity of colds and flu and help prevent constipation.

"I encourage patients to drink eight to 10 cups of water each day. Those who do report that they generally feel better," notes Ms. Dunn.

How do you know if you are drinking enough water? "A good test is to look at your urine," points out Ms. Dunn. "If it’s clear or pale yellow, you’re doing a good job of staying hydrated. But if it’s intense yellow or gold, you probably need to drink more water."

But not everyone likes water. Many people prefer soft drinks, fruit juices, sports drinks, coffee and other drinks. All these drinks can help quench your body’s thirst for fluids, but they typically contain 100 calories or more per serving.

"The best alternatives to water are diluted fruit juices, non-fat or skim milk and diet soft drinks," explains Ms. Dunn. "But these drinks shouldn’t supplant water. Take note of how much sugar is in these alternatives. Sugar slows down the rate at which fluid is absorbed into the body. If you have trouble drinking water because you don’t like the taste, try adding a twist of lemon or lime or a splash of fruit juice. And cold water tastes better."

Ms. Dunn notes that while bottled waters are very popular, tap water works just as well and is more economical. It's also safe. The Environmental Protection Agency (EPA) regulates tap water and requires that it be analyzed for chemicals and bacteria. The Food and Drug Administration (FDA), which regulates bottled water, doesn't require that it be analyzed for these substances.

In addition to water and other drinks, many foods are also good sources of water. Juicy fruits like oranges, grapefruit, grapes, watermelon and apples can help keep you healthy and hydrated. Carrots, tomatoes, tuna, yogurt, cottage cheese, soups, rice and pasta also contain plenty of water.

"The key is to think and drink small amounts," suggests Dunn. "The easiest way to stay hydrated is to drink a half-a-cup of water (four ounces) each hour you’re awake. When you get in the car, take along something to drink. When you sit down to watch TV, have something to drink. When you go to a meeting, take along something to drink."

© Copyright 1995-2005 The Cleveland Clinic Foundation. All rights reserved

This article appears in the Health Extra Newsletter. For other articles or for more information about Health Extra, Click Here.
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To read more about this and related topics, see:
Dehydration and Your Child
High Peformance Nutrition for the Athlete

This information is provided by the Cleveland Clinic and is not intended to replace the medical advice of your doctor or health care provider. Please consult your health care provider for advice about a specific medical condition. For additional written health information, please contact the Health Information Center at the Cleveland Clinic (216) 444-3771 or toll-free (800) 223-2273 extension 43771 or visit This document was last reviewed on: 6/24/2002

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