Friends who had a swimming pool also had a little sign posted that said, “We don’t swim in your toilet. Please don’t pee in our pool.” Despite such widespread admonitions, four fifths of those questioned believe that their fellow swimmers are guilty of relieving themselves without bothering to get out and find a bathroom. And one in six people polled admitted that they have indeed peed in the pool.

That’s the result of a survey conducted by the Water Quality and Health Council, which is sponsored by the chemical industry, which wants to sell pool chlorine, and which partners with the Centers for Disease Control and Prevention to get the word out on healthy swimming habits.

Here are some tips from the CDC:

Don’t swallow pool water. Don’t worry, I won’t.

Shower with soap before swimming.

Wash your hands after using the bathroom or changing diapers before getting in the pool.

The CDC also feels compelled to remind people that if they have diarrhea they shouldn’t go in the pool. Talk about a few bad apples spoiling it for everyone.

—Steve Mirsky