Survival skills
A human being can survive an average of three to five days without the intake of water. The issues presented by the need for water dictate that unnecessary water loss by perspiration be avoided in survival situations. The need for water increases with exercise.
Drinking water
The amount of drinking water required is variable. It depends on physical activity, age, health, and environmental conditions. In a temperate climate under normal conditions, adequate water intake is about for adult women and for adult men. Physical exercise and heat exposure cause loss of water and therefore may induce thirst and greater water intake. Physically active individuals in hot climates may have total daily water needs of or more. The European Food Safety Authority recommends per day for adult women and per day for adult men.