Can You Drink Too Much Water?

Drink more water. That seems to be standard nutrition advice for consuming a well-balanced diet.  Why is water so important?  More than half of the weight of the body is water.  The body loses about 2-3 quarts of water every day.  If you're exercising or doing physical work in the heat, the loss can be much more. 

We need water to:

  • help move food through the digestive tract
  • carry nutrients and eliminate waste products
  • maintain body temperature
  • help prevent kidney stones

Water needs vary depending on weight, age, sex, calorie needs, level of fitness, activity level, health and temperature and humidity.  The Adequate Intake (AI) for total water set by the Dietary Reference Intake Committee of the National Academy Sciences is 125 ounces (about15 cups) per day for men and 91 ounces (about 11 cups) per day for women.  Their report states that about 80% of the estimated total water intake is met by drinking water and beverages, while the other 20% is derived from foods.

For a quick estimate, experts at the Mayo Clinic recommend dividing weight (in pounds) by two to calculate daily water needs (in ounces).  For example:  To calculate the fluid needs of a150 pound person's water needs: 150/ 2 = 75 ounces per day, then divide by 8 to convert the amount into cups:  75/8 = approximately 9.5 cups per day.

If you're physically active, drink a couple extra glasses.  You can also weigh yourself before and after exercise and drink 2 cups of fluid for every pound lost. According to Nancy Clark, MS, RD, author of Nancy Clark's Sports Nutrition Guidebook, the simplest way to tell if you are getting enough water is to check the color and quantity of your urine. If your urine is dark and scanty, it is concentrated metabolic wastes and you need to drink more fluids.  Urine should be pale yellow. Some vitamin supplements can color the urine, though, so this is not always a reliable indicator. 

But is it possible to get too much water?  Yes, it is. Drinking too much water in a short period of time can result in hyponatremia, a dangerous condition sometimes seen in endurance athletes.   The cause is usually drinking excessive amounts of water, such as 3 - 5 gallons of water in a few hours but kidney disorders that reduce urine production can also result in water intoxication.  Symptoms include headache, muscle weakness, confusion, convulsions and even death.  To reduce the risk of hyponatremia and water intoxication, guidelines recommend limiting fluid intake during times of heavy sweating to 4-6 cups per hour. 




1. Understanding Nutrition, Eleventh Edition by Eleanor Noss Whitney and Sharon Rady Rolfes, Wadsworth Group, 2008

2. Nancy Clark's Sports Nutrition Guidebook (Third Edition) by Nancy Clark. Human Kinetics, 2003 

3. Nutrition: Concepts and Controversies 11th Edition by Frances Sizer and Ellie Whitney, Wadsworth Cengage Learning, 2008