The body loses water primarily by excreting it in urine from the kidneys. Depending on the body's needs, the kidneys may excrete less than a pint or up to several gallons of urine a day. About 1½ pints (a little less than a liter) of water are lost daily when water evaporates from the skin and is breathed out by the lungs. Profuse sweating—which may be caused by vigorous exercise, hot weather, or a high body temperature—can dramatically increase the amount of water lost through evaporation.