How much water is there in the human body?

water in human body

Did you know that newborn babies have the most water? An average newborn is roughly 75% water, a level that decreases as we age, dropping to about 50% for an elderly person.

The amount of water inside the body throughout the course of its life also varies depending on what shape that body is in. The more muscular a body is, the more water it contains. Conversely, the more fat there is in a body, the less water there is, because the water-content of fat is low. Our vital organs, like the brain, lungs, heart, liver, and kidneys, contain between 65% to 85% water*, while bones contain around 30%.

*Source: Mitchell et al. The Journal of Biological Chemistry, 1945: 625-637