There is no chemical that will turn pool water a different color if you pee in it

We wish it were true but, alas, there is no chemical that turns pool water blue if someone pees in it. At Mel Magazine, Mike Rampton investigates:

“Most pools are 20,000 gallons (91,000 liters) or more, so to make a few ounces of urine show up as a bright color would take some serious chemistry,” says bzsteele, a former pool supplies store employee, who recalls new pool owners asking about the dye. “There are cheap tests that could detect urine, but things like sweat, detergent and lotions would also be likely to spike them, so you’d be thrown off by all kinds of false positives. And once the reaction had happened, I’m not sure how you would undo it and get the pool back to stable.”

There’s also the fact that disinfection byproducts, or DBPs — created when the chlorine in pools reacts with the endless streams of pee released into them — are far more harmful than chlorine or urine would be on their own. Haloacetic acid, trihalomethane and chlorite can all be created by chlorine and organic matter (sweat as well as pee) reacting together, and can lead to respiratory issues, eye complaints, “lifeguard lung” and asthma. Adding more volatile chemicals, then, is unlikely to improve matters. And although pool disinfection techniques that require less chlorine (such as UV light, saltwater and hydroxyl-based systems) are increasingly being taken up by pool owners concerned about DBPs, a color-changing substance to stop people peeing in the pool is still nowhere in sight.

“Peeing in the pool isn’t great for the water chemistry,” says bzsteele. “However, average pools are huge, have proper sanitation and great filtration where every drop is filtered and circulated multiple times a day. In the long run, whatever [dye] you added would probably be more expensive and worse for you and the pool equipment than just having a random kid pee in it every now and then.”

"The Eternal Lie of the Pools That Turn Blue If You Pee in Them" (Mel)

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