When the kidneys remove uric acid and urea, the body's waste products, these must be dissolved in water. If we aren't drinking enough water, wastes are not removed as effectively and may build up as kidney stones. Water contains dissolved salts. The salts regulate the distribution of water within the body. This, in turn, affects the functioning of the kidneys, for regardless of the amount of water taken in, the kidneys must still excrete a minimum of 10 ounces a day to eliminate poisonous waste materials.
Water also is vital for chemical reactions in digestion and metabolism.
It carries nutrients and oxygen to the cells through the blood and helps to cool the body through perspiration. Water also lubricates our joints. It is possible to lose a pint of liquid each day by just exhaling. The rate at which water is eliminated in each individual varies depending upon body metabolism, physical activity, hot or cold environment, or during illnesses. During illness such as fever, vomiting, and diarrhea, the body can lose 4 quarts of water a day or more.