Water is the principal fluid of human body. It constitutes approximately 75 per cent of the total bodyweight. Almost all body fluids are present as water solutions. For example, blood contains 98 per cent water. The main functions of water inside the human body are given below:
1. Water acts as medium in which various metabolic and a biochemical reactions take place.
2. Water helps in absorption of various nutrients present in the food in the digestive system. By serving as medium, it facilitates the digestion of food at various stages in the digestive tract.
3. Water serves as medium for transport of chemicals to and from cells.
4. Water helps in maintaining body temperature through perspiration.
5. Water helps in removal of waste materials from the body through urine.
The water balance in the body is primarily maintained by kidneys in conjunction with thirst mechanism.