Do you have any sources for that? The fact that we sweat would indicate to me that the skin is porous and not waterproof- at least from inside out. But I’m certainly lacking in an adept knowledge of human biology.
I’ve found that that hockers of water filtration systems for the shower head hype the quantity and toxicity of chemicals in our water. One online merchant said “5 pints of water” are absorbed in the average shower. I suspect that that volume was exaggerated but I was unable to find anything of scientific merit, only untrustworthy advertising hype.
Sweating isn’t the result of liquid diffusing across the skin. It’s the secretions of sweat glands that empty on to the skin - there’s a big difference. If liquids could diffuse across, you’d swell up like a balloon when you went swimming or took a bath, since the concentration of salts and other dissolved stuff is much higher inside your body than in most liquids you immerse yourself in.
Burn victims actually tend to die of dehydration, since their skin has been so damaged that it’s no longer waterproof, and all of their internal fluids evaporate out.
Expats, particularly the female ones, are cautioned never to sit down in the bath in Jakarta. And yes, ahem infections were quite common, especially among those women who had been there for less than three years. (It takes about six before you can more or less safely eat street food there.)
So there are… points where you’re vulnerable to bacteria, certainly, but if you don’t drink the stuff (or brush your teeth with it-- seriously), even rancid brown water with its own thriving ecosystem can’t do much.
J.B.S. Haldane wrote an article on 1928 called On Being the Right Size in which he says “A man coming out of a bath carries with him a film of water of about one-fiftieth of an inch in thickness. This weighs roughly a pound.” That’s one pint. (He also says a mouse would be carrying its own weight of water, and an insect would be in big trouble.)
Any more water than that runs off quickly, and probably wouldn’t have time to be absorbed. Some might soak into hair, but that’s dead anyway, so no matter.
If you really wanted maatthias, you could e-mail the company and, not only, ask them where they came up with their numbers, but also ask them if they really believe the body is absorbing two liters, five pounds of water during an average shower, seems a bit of a longshot.
Why not try a little empirical experimentation? Got a scale? Got a shower? Weigh yourself just before and just after an average shower. I’d suggest two rules for control: #1 If you have long hair, it should be either wet or dry for both weighings. #2 No peeing in the shower! (ick)
Yeah, it sounds like a dorky thing to do, but you gotta take a shower anyway, and weighing yourself takes up less time than spending all day on SDMB.
Doh! The obvious empirical evidence points to little absorption.
Also, I googled this a bit more and I think I’ve located the misunderstanding. The shower head water filter advertisers’ claim is that a person absorbs the equivalent chlorine in 5 glasses of (assumedly) tap water in a 5 minute shower.
I can see how that would quickly become absorbing 5 pints of water in the average shower. Either I mis-construed this on my own or I read someone else’s illogical step forward.
I think I will attempt the empirical test proposed this week though.