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Each day, a 70 kg body eliminates about: 1,5 liters of urine + 0,4 L of vapor expiration + 0,5 L of perspiration + 0,1-0,2 L of water in faeces ≈ 2,5 L of water eliminated / day
The body needs to replace the lost water: it needs at least 2,5 L of water/day (≈35 mg of water/kg)
The more active we are, the more water we should drink!