Water is an essential nutrient.

Explanation

i. Our body consists of about 65-70% water. Cells blood plasma contain 70% and 90% water respectively.
ii. Water acts as a universal solvent as it provides medium for many metabolic reactions.
iii. It also helps in transportation of dissolved nutrients to various parts of body.
iv. When there is a little loss of water from the body, functioning of the cell and thereby whole body gets distrubed.
Hence, water is an essential nutrient.