Ever wonder why it seems like nothing can quench your thirst quite like water? Well,  more than half our weight comes from water.  The body actually loses about 2-3 quarts of water every day.  And 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

How much water do we need?  Needs vary depending on your weight, age, sex, calorie needs, level of fitness, activity level, health and the environmental 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 consuming 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.

Recommendations for water may also be called fluid recommendations and include fluid from all sources, including beverages and food sources.  Many of the foods we eat contain 80-95% water. Caffeine-containing beverages, including some sodas, coffee, tea, and energy drinks have a slight diuretic effect which increases fluid losses if ingested in large quantities.

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. 

A very active person may want to weigh before and after exercise.  For every pound lost, they should drink 16 ounces of water to replace fluids lost. Signs of dehydration include thirst, fatigue, headache, weakness, vague discomfort, loss of appetite, dry mouth, reduction in urine and difficulty concentrating. 

Some tips to help you increase your water intake inclue:

1.      Keep a pitcher of water in the refrigerator that contains the amount of water you need daily. 

2.      Keep water with you - on your desk, in your car, on your kitchen counter, or by your favorite chair. 

3.      Flavor water with a slice of lemon or lime. Try seltzer water, club soda or sparkling mineral water flavored with lemon, lime, orange or a splash of fruit juice.

4.      Eat broth-based soups and water-rich fruits and vegetables.




1. Understanding Nutrition, Tenth Edition by Eleanor Noss Whitney and Sharon Rady Rolfes, Wadsworth Group, 2005

2. Stealth Health by Evelyn Tribole, The Penguin Group, 1998

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