Peeing in the Pool: More Harmful Than You Think

There’s a good chance you’ve done this in all innocence. You were having a good time in the water and didn’t want to get out and disrupt the fun. So you did it.

You peed in the pool.

This is a fairly common occurrence as one in five Americans have admitted to peeing in a public swimming pool in their lifetimes. I’d dare to say that’s a pretty conservative number. The thought process is that the chlorine that’s been added to the water should kill off anything harmful, right?

Well, a recent study has shown that maybe that’s not the truth. Maybe peeing in the pool isn’t as harmless as we all thought.

Researchers from China Agricultural University and Purdue University looked at what happened when byproducts of urine (like uric acid) and chlorine combine. The research group found that this caused dangerous chemical reactions.

The combination produces several harmful gases. One is cyanogen chloride, a gas that can harm the central nervous system, heart, and lungs if inhaled. Uric acid is linked to 34%-68% of this byproduct that wafts around indoor swimming pools.

Nitrogen trichloramine (NC₁₃) is a poisonous gas that can cause acute lung injury and is created when chlorine is combined with uric acid. The dangerous thing with this gas is that it builds up quickly. A study conducted over a four-day swimming competition showed that levels of NC₁₃ doubled after one day and continued to increase over the course of the meet.

Both nitrogen trichloramine and cyanogen chloride have been linked to chronic health issues among swimmers, life guards, and pool staff.

But isn’t chlorine supposed to kill anything harmful in the water? That’s what competitive swimmer and Olympian Michael Phelps thinks.

“I think everybody pees in the pool,” Phelps told Telegraph in 2012.” “It’s kind of a normal thing to do for swimmers. When we’re in the water for two hours, we don’t really get out to pee. Chlorine kills it so it’s not bad.”

That might not be entirely true, Mike.

Chlorine’s job is to kill bacteria, but it also reacts with chemicals in human waste and those harmful gases are a result; this is particularly harmful in indoor pools that aren’t well-ventilated. The World Health Organization has even identified it as one of the top three risk factors associated with pools: injury/drowning, microbial hazards, and chemical hazards.

What can you do about it if you’re a frequenter of public swimming pools?

The study suggests you avoid “the vicinity of urine release locations in pools”—i.e., anywhere with lots of children (or competitive swimmers). You can also pick public pools that are well-ventilated or better yet, outdoors.

Jing Li, professor of applied chemistry at China Agricultural University suggests the most obvious solution: don’t pee in the pool. It’s “a voluntary act for most swimmers” that can be avoided.

Additional chlorine could also help solve the problem. However, that’s just treating the problem instead of trying to prevent it in the first place.

Peeing in the pool isn’t the only habit people admitted to committing in a public swimming pool. A survey conducted showed that 11% of participants admitted to swimming with a runny nose, 6% with a full-blow cold. Less than 1% admitted to swimming while ill with diarrhea, but a separate study has shown that evidence of e coli can be found in more than half of public swimming pools. Some of that can be attributed to not showering before swimming, a mistake 43% of swimmers admit to making.

Don’t be deterred; the potential risks are far outweighed by the benefits of swimming. One European study states, “Overall, the available evidence supports that the health benefits of swimming during childhood and adulthood outweigh the potential health risks of chemical contamination. However, the positive effects of swimming should be increased by minimizing potential risks.”

We agree.