The principal functions of water in the physiological activity of the human body are based chiefly upon its use as a vehicle. It is a carrier or solvent of the nutrients, as well as of the products of catabolism, that is the breaking down of the tissues, and of the excreta. The average content of water for instance in the urine is 94 percent, and in the feces 76 percent. No physiological action could take place in the absence of water. Desiccation always means death, both to the animal and to the vegetable. There is an old Latin adage: Corpora non agunt nisi soluta, which signifies that bodies do not perform any of their peculiar functions unless they are in solution. This is particularly true of the nutrients which are active in the process of building up, that is what is known by physiologists as anabolism, and in the processes of decomposition which produce the phenomena of catabolism. Water in some form is the universal necessity of the human organism. Not only is water taken as such into the system in the ordinary process of eating, but in all beverages, none of which are entirely devoid of water. Tea, coffee, and milk are composed very largely of water; even distilled alcoholic beverages are usually more than half water, while the fermented beverages are from 85 percent to 95 percent water. Experience has shown that of the five pounds of food eaten by a man of average weight in a day, fully three-fourths or four-fifths are water, the total quantity of dry food in a day being only about one pound and a half, while the total quantity of moist food is 5 or 6 pounds. Water therefore forms approximately four-fifths of the diet of the human race. Hence it is the most important beverage, both in quantity and in function, of all those to which man is addicted.

1 Data furnished by Surgeon General's Office, Public Health Service.