How many glasses of water should you drink each day?

Men should drink about 13 cups of water each day, while women should drink 9 cups per day, according to a source cited by the Mayo Clinic. However, the clinic suggests simply drinking enough water each day to replenish what water the body lost.

The body loses water through sweat, urine and bowel movements. The Mayo Clinic states that without enough water each day, the body becomes dehydrated. Base daily water intake on activity level or other circumstances that cause water loss. With exercise or an illness with fever, it is advisable to drink more. However, certain illnesses such as heart failure require limiting water intake.