Over 70 % of the adult body is made of water. Our body cannot function without water : a human will die faster of thirst than of hunger. A 68 kg person has about 40 liters of water in the body. 23-26% is found inside the cells, 7,5 % in the space between the cells and up to 4 liters in the blood. This volume must be kept constant. Food does not deliver enough moisture; doctors say we should drink ...