There's Way More Pee in Swimming Pools Than You Ever Thought

Scientists have answered one of the most pressing questions concerning swimming pools everywhere: Just how much urine is floating around in there?

Led by graduate student Lindsay K. Blackstock, researchers at the University of Alberta were able to convincingly gauge the level of pee harbored by most commercial swimming pools by testing for an artificial sweetener called acesulfame K, or Ace-K. Researchers note that the sweetener -- which is present in any number of widely consumed foods and doesn’t break down in chlorinated water -- provides the best barometer for measuring the level of urine at your local park's pool. In other words, if you're swimming through Ace-K, you're most likely swimming through piss.

Citing samples from hotels and recreational facilities in the United States and Canada, Blackstock and her colleagues determined that your average 222,000 gallon pool harbors roughly 20 gallons of urine. While it seems like a negligible amount, the interaction of pee and chlorine can occasionally make for a volatile concoction. As NPR reports: “Chlorine reacts with urine to form a host of potentially toxic compounds called disinfection byproducts. These can include anything from the chloramines that give well-used pools the aforementioned odor, to cyanogen chloride, which is classified as a chemical warfare agent.”

But your pool is probably safe, despite the sneaky folks who use it as a public urination trough. Blackstock told The Guardian that the study serves to caution swimmers against urinating in the pool, because using a real toilet is courteous and hygienic: “We want to use this study to promote public education on appropriate swimming hygiene practices...we should all be considerate of others and make sure to exit the pool to use the restroom when nature calls.”

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Sam Blum is a News Staff Writer for Thrillist. He's also a martial arts and music nerd who appreciates a fine sandwich and cute dogs. Find his clips in The Guardian, Rolling Stone, The A.V. Club and Vice. He's on Twitter @Blumnessmonster.