Why Do Pools Smell Like That?

(Last Updated On: July 10, 2022)

It’s summertime, which means you might be thinking it’s pool time. Maybe your last pool memories are from childhood and learning how to swim in a public one. If you have any memories of a public pool at all, you definitely remember “pool smell.” For a long time you probably just thought it was because they chlorinated the pools. Which isn’t entirely wrong, but it’s not the whole story. So why do pools smell like that?

It’s Not Chlorine

For the record, though, they do put chlorine in pools. A properly managed pool shouldn’t have much of an odor at all. Which is a hint about where this is going. But before we explain what’s making the smell, let’s explain how chlorine actually cleans a pool.

Chlorine is introduced into pools either through chlorine gas or a hypochlorite (typically sodium, calcium, or lithium hypochlorite). When chlorine is introduced to the pool it creates free chlorine, which acts as a disinfectant.

The distinct odor coming from a pool comes from chloramines. They’re created when chlorine reacts with ammonia, which humans bring a lot of into pools. You bring in ammonia through your spit, sweat, and snot. Even bugs that land and die in the pool will contaminate pools with ammonia. If you know some chemistry facts, you know that ammonia is also found in your pee. 

It turns out that the vast majority of things we associate with chlorine in pools is actually associated with the chloramines created from our contaminants (you peeing in the pool). You know, not only the smell, but also the irritated skin or eyes. Chloramines in pools are far weaker disinfectants than free chlorine floating around in a pool, and because they are formed using free chlorine they also reduce the ability of chlorine to disinfect your pool. They do have disinfecting properties though, and may be used to treat drinking water. 

Don’t worry, the EPA isn’t peeing in your water.

How much pee is in the pool though?

It’s not really a secret that the primary ammonia source in a pool is from either urine or sweat. A survey in 2012 found that almost one in five adults pee in the pool, with professionals being the most frequent offenders. That’s just the people who admit to peeing in the pool, by the way.

Also your pee can create other nasties that probably aren’t great for you

Anyway, stop peeing in the pool.


Wonder if there’s pee in any of these TV pools?

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About Kyler 727 Articles
Kyler is a content writer at Sporcle living in Seattle, and is currently studying at the University of Washington School of Law. He's been writing for Sporcle since 2019; sometimes the blog is an excellent platform to answer random personal questions he has about the world. Most of his free time is spent drinking black coffee like water.