Most people drink water throughout the day because it's refreshing and tastes good. But did you know that H2O is also necessary for your body's proper functioning? How much do you need?

Key Functions of Water

The human body is 60 percent water; this essential nutrient helps fuel many important chemical and metabolic processes, explains Stella Metsovas, BS, CCN, a California-based food, health, and nutrition expert.

Some vital roles water plays in the body include:

  • Feeding your cells: The water in your blood helps to carry oxygen and other important nutrients to your cells.
  • Fighting off illness: Water in your lymph fluids helps your immune system fight off germs. Lymph fluids travel through the lymphatic vessels, part of the circulatory system.
  • Digesting food: Water works with digestive enzymes in your salvia to help break down foods so the nutrients can be transported for absorption and assimilation.
  • Eliminating waste: Water plays a part in eliminating waste from your intestines, kidneys, and liver through perspiration, urination, and defecation. Water can also keep your stools soft so they will be easier to pass.
  • Regulating temperature: Water helps your body to maintain its ideal temperature by releasing excess heat to help you stay cool.
  • Lubricating organs, tissues, and joints: Water helps the body achieve proper moisture levels, and lubricates tissues and joints to keep them functioning well.

Water Boosts Your Game

Upping your water intake significantly for five to six hours before engaging in strenuous
exercise can also help you improve your athletic performance, according to Scott Mazzetti, PhD, Associate Professor of Exercise Science at Maryland's Salisbury University. Drinking water during exercise helps increase blood flow to bring oxygen to the muscles so they will work better. Water also helps to cool your skin and regulate body temperature.

How Much Water?

Not sure how much water you need? Six to eight cups (one cup is eight ounces) a day is a good place to start, but Metsovas says that there's no simple answer, since an individual's water needs depend on many variables. "We lose a fair amount of water if we engage in healthful day-to-day living," she says, adding that she recommends walking at least 8,000 steps daily to maintain a healthy activity level. "Typically your body needs about 1½ to 2½ cups of water per hour of exercise." Metsovas points out that many exercisers weigh before themselves before and after activity, and drink 1½ liters of water for every 1kg of body weight lost during exercise.

In addition to your activity level, your size, diet, and the climate where you live all affect how much water you need. To determine how much water you should be taking in, Metsovas suggests downloading an app that calculates water needs based on your lifestyle to your smart phone, computer, or tablet.

Getting Hydrated

If the thought of gulping down liters of water doesn't appeal, take heart: "My top recommendations for those who are moderately active (getting the equivalent of a 1.5 to 3 mile a day walk at a 3-to-4 mile per hour pace) is to eat your water," Metsovas says. She suggests consuming vegetables and fruits that have high water content, such as:

  • Cucumbers
  • Romaine Lettuce
  • Watermelon
  • Jicama
  • Apples

Not only are these foods high in water, they also offer added benefits: One medium apple, for example, supplies 14 percent of the daily value of vitamin C and almost 20 percent of the daily recommended amount of fiber. Some people like to replace one or two glasses of water with milk or fruit juice, but remember that juices don't have as much fiber as whole fruits. And unlike these alternatives, plain water is calorie-free.

Check Yourself

Finally, there's a simple way to know if you're getting enough water: by paying attention to the color of your urine. Urine from healthy individuals is usually pale yellow; darker yellow urine often indicates a lack of water in the body, and signals that you need to drink more. It's a signal you should pay attention to, since you can't rely on thirst as an indicator: By the time you're aware that you're parched, you're already slightly dehydrated.

Stella Metsovas, BS, CCN, and Scott Mazzetti, PhD, reviewed this article.


Scott Mazzetti, PhD, Associate Professor, Exercise Science Program Director, Salisbury
University. Email interview Sept. 10, 2013.

Stella Metsovas, BS, CCN. Email interview Sept. 9, 2013.
United States Department of Agriculture. Household Commodity Fact Sheet. "Apples,
Fresh." Code: F510-F515 April, 2009. Accessed September 26, 2013.