About body water

[Zipporah Schumaker]

Water accounts for about one half to two thirds of an average person’s weight. Fat tissue has a lower percentage of water than lean tissue and women tend to have more fat, so the percentage of body weight that is water in the average woman is lower (52 to 55%) than it is in the average man (60%). The percentage of body weight that is water is also lower in older people and in obese people. The percentage of body weight that is water is higher (70%) at birth and in early childhood. A 154-pound (70-kilogram) man has a little over 10.5 gallons (42 liters) of water in his body: 7 gallons (28 liters) inside the cells, 2.5 gallons (about 10.5 liters) in the space around the cells, and slightly less than 1 gallon (3.5 liters, or about 8% of the total amount of water) in the blood.
Water intake must balance water loss. To maintain water balance—and to protect against dehydration, the development of kidney stones, and other medical problems—healthy adults should drink at least 1