During a day of normal activity, the body needs about two quarts of liquid to replace lost body fluids. About 48 ounces should come from drinking water and other hydrating beverages. The remainder, about two cups, comes from solid foods.
Doctors at the University of Florida College of Health and Human Performance say fruits and vegetables are 85 to 96 percent water, while steak is 50 percent. When exercising, 1/2 to 1 quart of fluids per hour is required to replace fluid lost from sweat during moderate physical activity.
In hot weather, the liquid requirement during exercise is higher, depending on temperature and activity. In addition, it's important to drink water before starting non-exercise outdoor activities, such as gardening.