Is It More Gross to Pee in a Pool or an Ocean? Microbiologists Weigh In

When I was seven, my best friend's mom revealed that when she was a little girl and peed in the pool, it turned red. From that moment on, I never peed in the pool again. While the scare factor worked (even though it's untrue), a 2019 Water Quality & Health Council study found that 37 percent of adults still believe that urine-detecting dyes are activated after peeing in a pool. The study also shared that 40 percent of Americans admit to urinating in the pool as an adult.

But is peeing in the pool that bad? And from a germ perspective, is it better or worse than going in the ocean?

What happens when we pee in a pool and is it dangerous?

Most pools use chlorine, a chemical that is able to kill harmful bacteria. As long as pools are properly chlorinated, the good news is there are no real dangers when peeing in a pool, explains Jason Tetro, a microbiology expert and author of The Germ Files. “When chlorine mixes with urine, there’s a chemical reaction that can lead to the formulation of minute amounts of a toxic chemical known as cyanogen chloride," he says. "But, as the levels are so low, they’re near impossible to detect."

If you want to protect yourself as much as possible from any sort of urea in a communal pool, Chuck P. Gerba, Ph.D., Professor of Microbiology and Environmental Sciences at the University of Arizona, suggests staying away from the kids' shallow areas. “Children don’t have great sanitary habits and as wading areas are only a foot-or-so deep, the chlorine gets used up quite fast,’ he explains.

What happens when we pee in the ocean and is it dangerous?

The news is even better for the ocean urinators, with nothing really happening when in natural seawater. “Don’t worry about urea in the ocean," says Dr. Gerba. "Fish and mammals are peeing and pooping in there all the time. Your contribution to the ocean is insignificant."

And if you’re concerned about what your pee can do to vulnerable sea creatures such as coral, Jack A. Gilbert, Ph.D., a professor at the University of California San Diego, explains that there’s no harm. “Even if all the people swimming over a coral reef peed simultaneously, the number of bacteria or nitrogen released would still be a ‘drop in the ocean,’ literally.”

Are there different germs in pools vs the ocean?

As humans, we’re walking bacteria. Any human body is estimated to carry 39 trillion microbial cells that include bacteria, viruses, and fungi—all living on and in us. These cells are released into the air at a rate of 30 million an hour, explains Professor Gilbert. “We don’t have data on how many are released in water, but I can guarantee it would be a lot more, maybe 300 million+ an hour,” he estimates.

While this isn’t an issue as long as the pool is properly maintained, Professor Gerba warns that there is one parasite that chlorine won’t attack, cryptosporidium; an illness that gives the infected person diarrhea and loose stool. While anyone can catch it, it’s commonly caused by swallowing recreational water, according to New York State Health.

In the ocean, the majority of the microbes are harmless. However, some studies investigating beach microbiomes have also found pathogens such as Staphylococcus and Enterobacteriaceae, the family of fecal bacteria.

Which is more acceptable, germ-wise?

While there isn’t a significant microbiological risk when it comes to urinating in the pool versus the sea, all three microbiology experts agree that germ-wise, you’re better off going in the ocean. “There is simply more volume to dilute and reduce the risk,” says Tetro. “While disinfecting the pool is a great way to stay safe, the chlorine does eventually deplete. As a result, a pool could end up being a risk without proper monitoring.”

If these findings have now made you concerned about pools, follow this rule: If you can smell the chlorine, you’ll be fine. And as Dr. Gerba says, “It’s the poop, not the pee, that you should be worried about.”