We all know it’s gross—but how bad is peeing in a pool, really? Science has some surprising answers.
Surveys suggest around 40% of American adults admit to peeing in pools, and testing confirms it: one study found that a 220,000-gallon pool contained nearly 20 gallons of urine. That means if you’re swimming this summer, chances are you’re not just diving into water.
The real issue isn’t the urine itself—it’s the chemistry that follows. Urine contains nitrogen-rich compounds like urea and ammonia. When those mix with chlorine, they form disinfection byproducts (DBPs), including chloramines. These chemicals don’t just linger in the water; they can also evaporate into the air, creating that strong “chlorine smell” often mistaken for cleanliness.
Too many chloramines can cause eye, skin, and lung irritation, especially for people with asthma or other respiratory conditions. Poorly ventilated indoor pools are particularly risky, since the gases tend to hover above the water’s surface where swimmers breathe them in.
From an infectious disease perspective, urine in a well-chlorinated pool isn’t typically dangerous—unlike feces, which can spread serious illness. Still, every time someone pees, it weakens chlorine’s ability to disinfect the water, making the pool less effective at killing bacteria and viruses overall.
Even saltwater pools aren’t immune. They generate chlorine through a chemical process, so urine triggers the same chemical reactions.
Is one bathroom break in a huge pool the end of the world? Probably not. But if multiple swimmers are doing it, the effects add up quickly. Sweat, skin cells, and hair also contribute to the problem, meaning chlorine is already busy working overtime.
Bottom line: Holding it isn’t just good manners—it’s better science. Pee belongs in the bathroom, not the pool.
