The Institute of Medicine recommends that men living in temperate climates consume approximately 13 cups, or three liters, of water or other liquids per day. Women require approximately nine cups.
Climate, overall health and activity level influence how much fluid an individual needs to drink in a day. People who engage in heavy exercise or work outdoors require increased liquid intake to compensate for fluids lost by sweating. High altitudes, hot weather and conditions such as vomiting and diarrhea also deplete fluids. Women who are nursing also require a higher fluid intake. In addition to water, all liquids consumed during the day help maintain adequate hydration.