"We don't swim in your toilet, so please don't pee in our pool"

-- Sign spotted by Jon Caroulis, of La Salle University

AMERICANS who tote around bottles of hand sanitizer to ward off the swine flu now have something else to be skeeved about. Sorry to lay this on you right before Memorial Day weekend, but one in five Americans admits to peeing in a public pool.

Gross, right? But this statistic is from a new study that landed in my inbox recently, from the Water Quality and Health Council. And what the council discovered is that although most people don't own up to having urinated in a pool, swimmers do suspect their fellow bathers of engaging in all kinds of unhygenic practices in the water.

In fact, eight in 10 of those surveyed think other swimmers are guilty of going potty in the pool. Kids get a bad rap for doing this. I almost never get alarmed until I see someone getting into the water with a baby in her arms. Those disposable swimsuit diapers can do only but so much.

But from what I hear, it's not just a kid thing.

"I was a swimmer in college and competed at an international level throughout my career," Ashley (who doesn't want her last name used) wrote in an e-mail yesterday. "If you are looking for any real-life or personal anecdotes, I can say that it's probably way more than one in five people who pee in pools – it's just that no one admits it (even competitive swimmers)! But once someone eventually comes clean, other people admit to doing the exact same thing!"

Garth Chouteau wrote me about how his late grandfather, a physician in New York, once spiked poolside drinks with a harmless, invisible dye that, once it passes through the body, comes out as dark blue or green urine. "My grandfather was convinced that it was the many young people using the pool who were perpetrating the in-pool peeing, but it turned out it was the adults," Chouteau said in an e-mail.

Yesterday, I learned that the problem with urine isn't so much with the waste itself but that it "has a lot of things in it that react with the chemicals and make chlorine less effective and more irritating to people's skin and eyes," pointed Tom Lachocki, chief executive of the National Swimming Pool Foundation.

But let he who is without fault make the biggest splash. If some folks aren't using the pool as a potty, they may be doing other things that don't exactly qualify as hygenic. A third of those surveyed by the Water Quality Council admitted to jumping in the water without showering first. Everyone knows you're supposed to at least rinse off before going in. Yet, how many times have you said to yourself, "What difference does it make?" and plunged right in? And even if you were diligent about showering before taking a plunge, three-quarters of those surveyed think their fellow swimmers don't bother. If true, this could make for a nasty set of circumstances.

"If you get a lot of people that don't shower, it puts a lot of pressure on the disinfectant," Chris Wiant, chairman of the Water Quality Health Council, explained yesterday. "And what happens is that all the available chlorine consumes that bacteria and if that residual level decreases, the next load of bacteria that comes in, there's no chemical to disinfect it."

So, what are you supposed to do, besides staying out of pools where the water is cloudy and the tile feels slimy? The council says don't swim if you have diarrhea, shower with soap before swimming and take your kids on frequent bathroom breaks.

"People have to realize that when they are using pools, in essence, it's communal bathing," said Lachocki, of the swimming-pool foundation. "Anything you do to reduce the amount of contaminant you put in the water, the better everyone will be." *

Send e-mail to heyjen@phillynews.com. My blog: http://go.philly.com/heyjen.