# The human body is \_\_\_\_ percent water **URL:** \ **Category:** Factual Questions\ **Created:** [July 3, 2017, 12:48pm UTC](https://boards.straightdope.com/t/the-human-body-is-____-percent-water/790423 "2017-07-03T12:48:15Z")\ **Posts on this page:** 11\ **Page:** 1
**Author:** ![Peter\_Morris](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/peter_morris/32/359_2.png) [@Peter\_Morris](https://boards.straightdope.com/u/Peter_Morris)\ **Post date:** [July 3, 2017, 12:48pm UTC](https://boards.straightdope.com/t/the-human-body-is-____-percent-water/790423/1 "2017-07-03T12:48:15Z")
How much of the human body is water? Firstly, what about actual liquid water? There’s water in the blood plasma, and water in the protoplasm inside cells, and various other fluids in the body. How much is there as a percentage by weight or by volume? (contents of the stomach, intestines or bladder don’t count) Secondly, there are more complex molecules such as proteins that contain hydrogen, oxygen and other elements. When a body is cremated, they break down into water and other stuff. How much water does a cremated body produce? ---
**Author:** ![naita](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/naita/32/5862_2.png) [@naita](https://boards.straightdope.com/u/naita)\ **Post date:** [July 3, 2017, 1:19pm UTC](https://boards.straightdope.com/t/the-human-body-is-____-percent-water/790423/2 "2017-07-03T13:19:48Z")
[Depending on age and body mass composition the human body varies from 45% to 75% by weight](https://en.wikipedia.org/wiki/Body_water). Since solutions take up less space than their separate parts of water and solute the percentage by volume will be higher. ---
**Author:** ![naita](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/naita/32/5862_2.png) [@naita](https://boards.straightdope.com/u/naita)\ **Post date:** [July 3, 2017, 1:27pm UTC](https://boards.straightdope.com/t/the-human-body-is-____-percent-water/790423/3 "2017-07-03T13:27:06Z")
[9% of the body’s mass is hydrogen](https://en.wikipedia.org/wiki/Composition_of_the_human_body) (An average of some sort of course, but it will vary less than the water content.) Hydrogen is only 1/9th mass of water so if all the hydrogen became water cremating a body would create water equivalent to 81% of the original body mass. I’m sure though there are a lot of compounds that wouldn’t want to give up their hydrogen to oxygen, so that’s an upper bound. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [July 3, 2017, 2:27pm UTC](https://boards.straightdope.com/t/the-human-body-is-____-percent-water/790423/4 "2017-07-03T14:27:06Z")
> [@](#): > > I’m sure though there are a lot of compounds that wouldn’t want to give up their hydrogen to oxygen, so that’s an upper bound. Probably not. Elemental oxygen is one of the most reactive substances around. Given the choice between combining with oxygen and combining with almost anything else, almost everything will choose the oxygen. ---
**Author:** ![watchwolf49](https://avatars.discourse-cdn.com/v4/letter/w/e9c0ed/32.png) [@watchwolf49](https://boards.straightdope.com/u/watchwolf49)\ **Post date:** [July 3, 2017, 5:17pm UTC](https://boards.straightdope.com/t/the-human-body-is-____-percent-water/790423/6 "2017-07-03T17:17:36Z")
> [@naita](#): > > [snip] … I’m sure though there are a lot of compounds that wouldn’t want to give up their hydrogen to oxygen, so that’s an upper bound. It’s more like most compounds will want to give up their hydrogen _for_ oxygen, making carbon dioxide … the loose hydrogen then takes up with oxygen to make water … Oxygen is a powerful oxidizer … ---
**Author:** ![bonzer](https://avatars.discourse-cdn.com/v4/letter/b/45deac/32.png) [@bonzer](https://boards.straightdope.com/u/bonzer)\ **Post date:** [July 3, 2017, 10:36pm UTC](https://boards.straightdope.com/t/the-human-body-is-____-percent-water/790423/7 "2017-07-03T22:36:53Z")
While the history hasn’t been asked about, the famous determination of the water content in humans was by [Francis Moore](https://www.nap.edu/read/11807/chapter/15). There was a good article about him by Atul Gawande in the _New Yorker_ back in May 2003. ---
**Author:** ![snfaulkner](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/snfaulkner/32/433_2.png) [@snfaulkner](https://boards.straightdope.com/u/snfaulkner)\ **Post date:** [July 3, 2017, 10:47pm UTC](https://boards.straightdope.com/t/the-human-body-is-____-percent-water/790423/8 "2017-07-03T22:47:43Z")
I’m what they call a water man, Jack. ---
**Author:** ![Dr.Strangelove](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dr.strangelove/32/6613_2.png) [@Dr.Strangelove](https://boards.straightdope.com/u/Dr.Strangelove)\ **Post date:** [July 4, 2017, 12:01am UTC](https://boards.straightdope.com/t/the-human-body-is-____-percent-water/790423/9 "2017-07-04T00:01:04Z")
> [@Chronos](#): > > Probably not. Elemental oxygen is one of the most reactive substances around. Given the choice between combining with oxygen and combining with almost anything else, almost everything will choose the oxygen. And if this ever weren’t true, you’re probably in very bad shape, because it means you have some fluorine in you. > [@snfaulkner](#): > > I’m what they call a water man, Jack. You know what they put in children’s ice cream, Mandrake? ---
**Author:** ![naita](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/naita/32/5862_2.png) [@naita](https://boards.straightdope.com/u/naita)\ **Post date:** [July 4, 2017, 11:01am UTC](https://boards.straightdope.com/t/the-human-body-is-____-percent-water/790423/10 "2017-07-04T11:01:06Z")
> [@watchwolf49](#): > > It’s more like most compounds will want to give up their hydrogen _for_ oxygen, making carbon dioxide … the loose hydrogen then takes up with oxygen to make water … > > Oxygen is a powerful oxidizer … I meant “a lot” as in “many different”, not as in “a large percentage”, but on further thought I see that even that was wrong. ---
**Author:** ![Leo\_Bloom](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/leo_bloom/32/10377_2.png) [@Leo\_Bloom](https://boards.straightdope.com/u/Leo_Bloom)\ **Post date:** [July 4, 2017, 8:13pm UTC](https://boards.straightdope.com/t/the-human-body-is-____-percent-water/790423/11 "2017-07-04T20:13:20Z")
> [@Dr.Strangelove](#): > > And if this ever weren’t true, you’re probably in very bad shape, because it means you have some fluorine in you. > > You know what they put in children’s ice cream, Mandrake? No fair username/post combo. ---
**Author:** ![Dr.Strangelove](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dr.strangelove/32/6613_2.png) [@Dr.Strangelove](https://boards.straightdope.com/u/Dr.Strangelove)\ **Post date:** [July 4, 2017, 9:10pm UTC](https://boards.straightdope.com/t/the-human-body-is-____-percent-water/790423/12 "2017-07-04T21:10:44Z")
> [@Leo\_Bloom](#): > > No fair username/post combo. To be fair, fluorine in the form of sodium fluoride or other compounds used to prevent tooth decay is a _very_ different thing from, say, hydrogen fluoride or diatomic fluorine. But I couldn’t help but play on the connection there, especially with my username :).