Most doctors recommend drinking 1,900 milliliters, or eight glasses of water a day as a general rule to ensure adequate hydration. This figure does not include the amount of water that is in food and other beverages consumed throughout each day. The Institute of Medicine has a separate recommendation for men and women based on the total water intake from water, food, and other beverages. The IOM recommends roughly 2,700 milliliters, or 91 ounces for women and 3,700 milliliters, or 125 ounces daily for men.
Water Needs Vary with Activity
Anyone engaging in physical exercise requires more than 1,900 milliliters of water daily to replace bodily fluids lost through sweat. To estimate how much water is needed during rigorous exercise an athlete should weigh himself before and after exercising for a few days to obtain an average weight loss. In addition to the recommended average water consumption intake, for each pound of body weight lost, 470 ml to 705 ml of water, or 16 to 24 ounces should be consumed.
Drinking enough water to prevent feeling thirsty is a method that will ensure adequate water intake in lieu of actually measuring the volume of water. Consult with your doctor to obtain a recommendation about the amount of water that is most appropriate for your lifestyle and activity level.