Why does drinking too much water or surviving only on water kill you ?
Water is the universal solvent and makes up most of our body weight. The cytoplasm in all our cells is mainly water. The blood contains mainly water in the plasma. However, if someone drinks too much water rapidly, the body cannot maintain equilibrium. The higher concentration of water outside the cell membranes of all the body cells compared to the lower concentration inside the cells, will create a concentration gradient. Inward osmosis will occur and eventually, the cells could burst. If someone tries to live only on water, while water is necessary to maintain the amount of fluid in the body, it does not contain any calories that could provide the body with the energy it needs to function. Thus, the body will go to the fat reserves first for energy, and eventually, to the protein which results in the muscles wasting away and eventually death by starvation.