The human body is composed of billions and billions of cells, and every one of those cells needs water in order to survive.
The water you consume through the food you eat and what you drink follows a very precise route to arrive in your cells. After passing through the stomach, water enters the small intestine, where it is largely absorbed in the first sections, the duodenum and the jujenum. The rest passes into the colon, where it crosses the intestinal mucous membrane into the bloodstream, and then into the interstitial tissues that makeup the framework of every organ, to finally arrive in cells.
Water in the cells
At the most foundational level, water is necessary for all cells—human or otherwise—to carry out the chemical reactions that allow them to live. Water enables hydrolysis, a vital process by which cells breakdown what we eat (lipids, proteins, and carbohydrates) and create energy. But if we go “up” a level or two in size and scale, the role of water in the human body becomes more readily comprehensible, and relatable.
Water on a bigger scale
The body needs water to perform all of the following functions: regulating body temperature, lubricating joints, moistening tissues in the mouth, eyes, and nose, helping to dissolve nutrients and make them accessible in the bloodstream, carrying nutrients and oxygen to cells, and for flushing out waste products. In other words, nearly everything that the body does requires water.