Exact water intake needs vary based on personal factors, but Mayo Clinic reports that men need approximately 3 liters (3000 mL) per day, and women need approximately 2.2 liters (2200 mL). These standards are based on a healthy person living in a temperate climate. Additionally, the figures are based on total beverage consumption, which can include liquids other than water.
Mayo Clinic's standard is based on a study by the Institute of Medicine, which stands in contrast to the common-knowledge rule of eight glasses of water per day. People who are more active or who live in more humid climates sometimes need more water because they lose more water through breathing and perspiration. Certain health conditions cause variance in water needs, as well. It is important to consume adequate amounts of water during the day, as insufficient water intake leads to dehydration.