The DU Lounge

It's not chlorine we smell. It's chloramines, caused by urine (and sweat) combining with chlorine.

Just How Much Pee Is In That Pool?

You know that sharp odor of chlorine from the swimming pool you can recall from earliest childhood? It turns out it's not just chlorine, but a potent brew of chemicals that form when chlorine meets sweat, body oils, and urine.

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The scientists calculated that one 220,000-gallon, commercial-size swimming pool contained almost 20 gallons of urine. In a residential pool (20-by-40-foot, five-feet deep), that would translate to about two gallons of pee. It's only about one-hundredth of a percent, but any urine in a swimming pool can be a health concern for some people, not to mention that smell that never quite goes away.

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Apart from being gross, that's also a potential health hazard. 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. There are also nitrosamines, which can cause cancer. There's not enough evidence to say whether the nitrosamine levels in pools increase cancer risk, Blatchley says, but one study in Spain did find more bladder cancers in some long-term swimmers.

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The simplest solution: Just don't pee in the pool. And tell all your friends not to do it, either. "I view it like secondhand smoke," Blatchley says. "It's disrespectful and potentially dangerous."

https://www.npr.org/sections/health-shots/2017/03/01/517785902/just-how-much-pee-is-in-that-pool