For many people, the height of summer means it’s time to take a dip in your local swimming pool. What could be better, after all, than spending a hot day splashing around in crystal-clear blue waters—even if those waters often have a bit of a chemical smell to them?

Many of us assume that the reason our pools smell like chlorine is simply that they’re filled with, well, chlorine. This is technically true, but in actuality, the smell we associate with chlorine results from the interaction of bodily fluids like sweat, body oils, cosmetics—and yes, potentially urine—with chlorine.

Ultimately, though, pools really shouldn’t smell too strongly of chlorine. If yours does, that may be a bad sign. 

What Is Chlorine?

Chlorine is an essential chemical element known by the symbol Cl and the atomic number 17. It is known for its ability to form compounds with many different elements. 

When chlorine is added to pool water, it reacts to form hypochlorous acid, a powerful disinfectant that can destroy bacteria, viruses, pathogens, algae, and other microorganisms that can be dangerous to swimmers.

Why Chlorine Smells

When chlorine enters pool water, it also helps oxidize organic compounds like urine, sweat, body oils, cosmetics, and other substances that often accompany human bodies, especially on hot summer days. 

Chlorine does this by releasing two chemicals upon entering our swimming pools: hypochlorous acid and hypochlorite ion. Together, these chemicals are known as “free available chlorine,” and when they interact with relatively clean pool water, they can easily kill any bacteria and contaminants. Ideally, when a pool is properly treated with chlorine, it won’t have a strong chlorine smell at all.

However, when hypochlorous acid interacts with ammonia, a chemical found in sweat and urine, it forms chloramines, which are sometimes referred to as “combined chlorine.” This chemical is typically the culprit behind any pool that smells overpoweringly like chlorine.

High concentrations of this chemical can lead to red eyes and skin irritation, and are sometimes associated with asthma and other health conditions, which occur most frequently in cases of prolonged indoor exposure. 

In short, if a pool smells overwhelmingly of chlorine, this might be an indication that the pool water is excessively dirty and full of contaminants like sweat or, unfortunately, pee.

What to Do If Your Pool Smells Excessively Chlorinated

If you have your own pool and find yourself hit by a huge waft of that chlorine smell every time you emerge from under the water, a bit of extra cleaning may be in order.

A strong chlorine smell may be an indicator that it’s time to look into alternative pool sanitation methods. These might include shock treatments, which involve filling your pool with specific products that break down chloramines.

It may also be time to invest in an additional sanitation system like UV sanitizers or ozone generators. You also may need to work to improve your pool’s circulation, encourage swimmers to shower, and avoid overcrowding. Hopefully, in no time you’ll truly be enjoying your pool—without that overwhelming chemical scent.

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