Most of the human body is water, with an average of roughly 70%. The amount of water in the body changes slightly with age, sex, and hydration levels.
Water exists throughout the body. Cells contain 60% of all water in the body, with roughly one-third of the remainder, surrounding the cells.
Some organs contain much more water than others. The brain and kidneys possess the highest percentage of water; the bones and teeth contain the lowest proportion.