Everyone knows there’s urine lurking beneath the surface of a public pool, but just how much of it there is on average would turn your stomach.
Researchers from the University of Alberta in Canada found that commercial-size swimming pools usually contain about 20 gallons of urine. For a good frame reference, that would be like a backyard or hotel pool having about two gallons of urine in it.
And according to sex expert Dr. Ruth Westheimer, that’s exactly why you should never have sex in one. Despite how attractive movies and television have always made the experience out to be, it’s actually one of the grossest things you can do.
“I think you can assume that if people are using your pool, they’re peeing in it,” says environmental engineer Ernest Blatchey III. “I view it like secondhand smoke. It’s disrespectful and potentially dangerous. It’s not uncommon for water in a pool to go unchanged for years.”
As you can imagine, urine swimming around in a pool only gets worse over time. Blatchey’s research shows that the formation of even more germs is encouraged as chlorine is added to the water, and it’s much more inexpensive for pool operators to just add more water and chlorine than it is to completely replace them.
So remember that the next time you’re partying by the pool, and some hottie is trying to entice you with some underwater action. Your health could depend on it.