You should drink water whenever you are thirsty. A persistent myth is that a person needs to drink 8 eight ounce glasses of water every day. While following this rule will cause no harm, it is completely unsupported by scientific evidence [1][2]. A person should replace the same amount of water he or she loses in a day. Water is lost through urination, bowel elimination, sweating, and breathing. Remember that drinking is not the only way to replace lost water: food contains a lot of water, and your body can absorb water through the skin. Again, the general rule is to drink water whenever you are thirsty or whenever you want some.
