The Truth Behind Clean (Or Not So Clean) Pools

Photo by Claes Pettersson on Unsplash

By Claire Alongi, Swimming World College Intern.

When swimmers are racing to the finish of their 100 free, they probably aren’t thinking of whether or not the pool is clean.  In fact, they probably don’t think of it much at all. It is a more or less acknowledged fact that everyone pees in the pool. Sometimes it’s the middle of the main set and you need to pee, so desperate times call for desperate measures. Maybe cleanliness is a little more on the mind of families climbing into a public pool teeming with other patrons, but after enough splashing around, they too push aside what might or might not be invisibly lurking in the water. After all, chlorine does all the bacteria killing work – right?

Well, not exactly. Despite measures to keep them squeaky clean, pools are not the most sanitary places to spend your time.

How Does the Chlorine in Pools Work?


Photo Courtesy: Courtney Flood

Before getting into what might be found in your friendly neighborhood pool, it’s important to understand how the main player, chlorine, works. Most people know that chlorine is what “cleans” pools, but they probably don’t know exactly how that happens. Chlorine works to disinfect pools by breaking down into different chemical compounds that eat away at the cell walls of harmful bacteria. For these compounds to effectively do their job, the pH of the pool – or how basic or acidic it is – needs to be between 7 and 8. Ideally it will be somewhere in the middle. Besides pools, chlorine can be found in many household cleaning products. Chlorine is pretty good at doing its job. It’s the humans that make it harder.

Why You Should Probably Stop Peeing in Pools


Photo Courtesy: ajay bhargav GUDURU

Peeing in pools is practically a hallmark of swimmer culture.  Whether it ranges from dirty secret to running joke, chances are that most (if not all) swimmers have peed in a pool at some point. And while it can be more convenient than leaving the water to brave a cold pool deck, peeing in the pool is not the best idea. A little pee in the pool won’t hurt anybody; however, when compounds in chlorine and the uric acid from urine mix, they can create substances that can be harmful in high doses.  

Trichloramine and cyanogen chloride are irritants when they release gas from the pool water. The former can be especially detrimental to those with respiratory problems. Sweat can also combine with parts of chlorine to form things like trichloramine, called chloramines. This could become a problem in a very crowded pool (likely public) where lots of people might decide they need to take a leak. But to be fair, these are unlikely to be an issue on a regular basis, because they decay quickly. But in the interest of public health, next time, just make the dash to the bathroom instead of going in the pool. In the meantime, there are more nefarious things that could be taking residence in your local pool gutter.

Things That Linger…


Photo Courtesy: Linda Griswold

People might get away with sneakily peeing in pools, but going number two is another story. If there’s poop in the pool, everyone gets out and the whole place should get deep chemical cleaning. But the tricky part is, someone doesn’t need to directly poop in the pool to deposit fecal bacteria in the water.  The CDC recently released a report on outbreaks of cryptosporidiosis, caused by the parasite Cryptosporidium, from 2009 to 2017. There were a total of 7,465 cases of cryptosporidiosis reported. 

The CDC describes cryptosporidiosis as “a profuse, watery diarrhea that can last up to three weeks in immunocompetent patients and can lead to life-threatening malnutrition and wasting in immunocompromised patients.” In the right conditions, it can live in a pool for seven days after an infected person who has recently had diarrhea goes into a pool. Of the recorded cases, 4,232 – or 56.7 percent – were reported as having come from what they described as “treated recreational water (e.g., in pools and water playgrounds)”. The CDC study discovered that Cryptosporidium is highly tolerant of chlorine.

What You Can Do to Have a Cleaner Pool

Hartwick College pool

Photo Courtesy: Hartwick College

Have no fear! Don’t let this article drive you out of the pool looking for a full body cleanse. If you’re maintaining your own pool, be sure to keep track of the chlorine and pH levels to make sure they’re at safe and optimum levels. Don’t go swimming if you’ve had diarrhea within the last two weeks. Stop peeing in the pool. And in general, don’t think of the pool as an all-in-one, germ-killing bath 2.0.

In fact, the CDC recommends the following in case of an outbreak: “If a cryptosporidiosis outbreak occurs, substantial decontamination measures are needed, including hyperchlorinating public treated recreational water venues (e.g., at a hotel, apartment complex, or waterpark) and using hydrogen peroxide to disinfect surfaces in child care settings to inactivate Cryptosporidium oocysts.”

The pool is where you go to practice or have fun. Even if you don’t think you’re dirty, be sure to rinse off before getting in the water to decrease the levels of human oils and other excretions that can combine with chlorine to create harmful chemical byproducts. Tell your friends to do the same. If everyone follows those few guidelines, pools will become cleaner faster than you can say “cryptosporidiosis”!

-All commentaries are the opinion of the author and do not necessarily reflect the views of Swimming World Magazine nor its staff.

1 comment

  1. avatar
    Leo Letendre

    You briefly mention the effects of sweat on water chemistry and that they can affect the level of chloramines. This has been known for some time. The fact that as swimmers we can be in a pool with a significant number of other athletes who are sweating due to their workout should not be ignored. Even though we don’t feel sweating when we workout doesn’t mean we aren’t sweating. Previous reports of the effect of sweat on pool chemistry indicated that sweat may be a bigger problem than peeing in the pool.