Nutritionists recommend a daily fluid intake of 1.5 to 2.5 liters for healthy adults in normal living conditions.
Fluid requirements rise significantly in hot weather or under increased physical strain and sweating, as for instance during sporting activities. In this case three or four liters a day can be required to compensate the loss of fluid. But there are situations in everyday life as well that necessitate an increased fluid intake. Dry office air thus can increase fluid requirements to double the usual amount.