Water is absolutely critical to life. They would not be able to function without water. The quantity of water in the body varies with the body fat. Fluids within the cells make up about three fourths of the total body water and the rest is found in the circulating plasma and as interstitial fluid, that is lymph and fluid which washes the tissues. The circulating plasma is about 5 per cent of the total body weight.
Water is a chemical compound of hydrogen and oxygen.
Some of the water in the body is acquired through the union of oxygen and hydrogen in the tissues but the greater part of it is acquired through our consumption of food and water by our body. Thirst is aroused by a mechanism within our bodies that regulates or controls the water balance in our body. Water is accordingly excreted or stored by the kidneys. It is most important that the fluid in our body remains balanced. The body is said to be in fluid balance when the available water equals that of the water excreted or lost from the body.