About 60% of body weight:
The distribution and movement of water in the body are essentially linked to the substances present in it, in particular sodium and potassium. Sodium is present in intracellular water (50-55% of total water) while potassium in extracellular water (15-20% of total water).
Water assumption has to compensate for its elimination with urine, feces, skin and breathing (water balance).
Water requirement is about 1.5-2 liters/day and varies according to diet, climate, physical activity, age and other physiological (ex. pregnancy) and pathological conditions.