Paranoid and carefree summer swimmers, take notice.
At least 17 percent of those smiling, splashing people admit to peeing in a pool, and 78 percent of people suspect their fellow swimmers are urinating in the water, according to a new study by the Water Quality and Health Council.
But that suspicious patch of warm water might not be the worst of what lurks in the pool, or the worst of possible unhygienic threats in summer fun.
Infectious disease experts, bacteriologists and parasitologists say some of what seems germy and gross is probably safe, while other summer fun has hidden dangers.
Although peeing in the pool was the most popular admonition, there are other poolside confessions that could cause more illness, according to the Water Quality and Health Council, which is sponsored by the Chlorine Chemistry Division of the American Chemistry Council.
Sixty-five percent of people reported that they skipped a shower before entering a pool, and it's unknown how many of those who bothered to shower took the step to use soap over a quick rinse.
"It's what a swimmer takes into the pool that makes others sick," said Linda Golodner, vice chairwoman of the Water Quality and Health Council. The Centers for Disease Control has found outbreaks of diarrhea, respiratory illness, ear and skin infections, all from a contaminated pool.
The worst infections come from -- you guessed it -- fecal matter. For that reason, the CDC recommends the following tips to keep your pool safe:
Don't swim when you have diarrhea.
Don't swallow pool water.
Practice good hygiene. Shower with soap before swimming and wash your hands after using the toilet or changing diapers.
Take your kids on bathroom breaks or check diapers often.
Change diapers in a bathroom or a diaper-changing area and not at poolside.
Wash your children thoroughly (especially the rear end) with soap and water before they go swimming.
Not that one should skip the tradition of a local pool. Unclean pool water accounted for 4,500 recreational water illnesses (RWIs) between 2005-2006, according to the CDC.
The trick, according to the Water Quality and Health Council, is to detect an unhealthy pool.
"First of all, use all your senses," Golodner said. That means look at the pool before entering and if it's clear down to the drain at the bottom, then it's likely clear of contaminants.
Golodner said using a sense of smell is important, too. An overbearing chlorine smell could actually be caused more from the chemical reaction of chlorine with urine than excessive amounts of chlorine itself. Once you're in the pool, Golodner recommends touching the sides. If the tiles feel slimy, that's likely algae growing there. Finally, Golodner says "never drink or swallow the water."
Outdoor grilling and barbecuing is a summertime staple but when it comes to cooking meat, precaution can be as valuable as a good spice rub.
Unfortunately for those who like their burgers rare, undercooked meat is a dangerous source of bacteria like E. coli and salmonella, which can make people sick or even kill them.
The 1993 E. coli outbreak at Jack in the Box hamburger restaurants, for example, brought the issue to national attention after hundreds of people were injured and four children died from eating mishandled meat products.