Nutritions - Water Water is the most significant component of organisms. About 65% of the human body is made up of water. Surprisingly, our brain consists of 85% of water. Water as an excellent solvent, is able to dissolve many substances; as a result, water provides a medium for transportation of useful substances and nutrition inside our body. It can also maintain a constant temperature due to its ability to avoid extreme temperatures. In a cell, water helps chemical reactions, therefore, to transform them to energy source.