The human body uses water for many things. In fact, the body itself is about two-thirds water.
Each time we breathe out, we lose a little water in the form of a gas called water vapor. Over the course of a whole day and night, we lose quite a bit of water just by breathing. We also lose water when we go to the bathroom, when we sweat, and when our eyes make tears. (The eyes are always making small amounts of tears, which keep the eyes moist and clean.)
Any one of those processes may not seem like much, but added together they use a lot of water. So it’s a good idea to drink some water several times a day to replace the water the body has used. After exercise, drink enough water to quench your thirst, then stop. Taking in too much water at one time can make you sick.
Photo by: Chris Brown/Alamy