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It’s that time of year again, when nothing seems more inviting than a dip in a cool swimming pool on a hot, muggy day. But boy, do we have a surprise for you.

A survey conducted by the Water Quality & Health Council has found that one in five adults urinates in public pools, according to a report by CBS Cleveland. And, we’re loath to point out, the findings do not account for the adults who simply didn’t own up to it. Nor do they account for children, whom we already suspected had zero scruples about this heinous act.

(MORE: The World’s Highest Swimming Pool)

The study also found that around 70 percent of swimmers don’t shower before entering a public pool, likely thinking something along the lines of, Well, I’m going to need a shower afterwards, so why clean myself beforehand? Well, smart guy, to keep swimming healthy for everyone, that’s why.

“The pre-swim shower removes a lot of the sweat, cosmetics and urine that can mix with chlorine to create irritants in pool water,” Michele Hlavsa, chief of the Center for Disease Control’s Healthy Swimming Program, told CBS Cleveland. “These irritants, not the chlorine itself, cause red eyes when we swim and the strong chemical smell of some pools.”

(MORE: CDC: 1 in 8 Public Swimming Pools Harbor Harmful Bacteria)

One note of caution here: the Water Quality & Health Council is sponsored by the Chlorine Chemistry Division of the American Chemistry Council, an industry trade association. So it’s not like they don’t have a swimmer in this race. But bathers, beware next time you jump into that clear, sparkling public pool. Who knows what could be lurking in those waters.

MORE: Are Urinating Swimmers Killing Fish?