An average adult body is 50 to 65 percent water -- that's roughly 45 quarts. Men are more watery than women. A man's body is 60 to 65 percent water, compared to 50 to 60 percent for a woman. In infants, the figure is a whopping 70 percent.

Water content differs throughout the body. Blood is made up of 83 percent water, bones are 22 percent water, and muscle is 75 percent water.

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Within single cells water content ranges between 70 and 85%. The percent water in the entire body by weight varies with age, sex, and physical conditioning. Heart and lung contain the most water, about 80%. Fat (about 20%) and bone (about 43%) are among the lowest. Therefore, the total body is an average of all organs, blood, and extracellular fluids.

What percentage of the human body is water, and how is this determined?