How many more actually do, but wouldn't admit it?

The poll of 1,000 adults was conducted in late April and early May of this year by the Water Quality and Health Council, a body of scientific and other experts who advise the American Chemistry Council, an industry trade association. One in five respondents (17 percent) admitted to urinating in the pool, while almost eight in ten (78 percent) are convinced that their fellow swimmers are guilty of this act. Plus, about a third (35 percent) jump in without showering first, and three-quarters (73 percent) think other swimmers do the same. Even though most people seem wary of the hygienic standards of the swimmers around them, only 36 percent say that pool water cleanliness is on their mind when they take the plunge.

Besides being just plain gross, filthy pool practices can lead to unsafe swimming conditions. Urine -- as well as sweat and even sunscreen -- contain nitrogen, which eats up a pool's free chlorine. Free chlorine is what kills waterborne germs that could make you sick if ingested. So if too many people are peeing in the pool or diving in while sweaty, that could mean less chlorine's available to wipe out nasty critters.

Link

The article goes on to list some "tips" to protect yourself and others. One of them is to not go swimming when you have diarrhea. We've hit a new low when that actually needs to be said.

Paging bananamo for a convoluted "I don't ____ in your ____, so don't ____ in my ____ ."

alright, here goes:

i don't shower in your urine, so don't swim in my pool.