Why swimmers' eyes sting in your pool

What stings the eyes

If your eyes burn after a swim, the chlorine itself is usually not the culprit. What actually causes that redness and stinging is what happens when chlorine comes into contact with the things swimmers carry into the water with them: dirt, sweat, pee, and traces of poop.

When chlorine mixes with that body waste, it can bind to it and form chemicals known as chloramines. These are the compounds responsible for the eye irritation many swimmers know all too well.

So the sting is a sign that the water is carrying more than just chlorine. It is chlorine that has already reacted with waste introduced by the people using the pool, and that reaction is what makes eyes red and sore.

It is not too much chlorine

Many people assume a strong chlorine smell means someone dumped too much chlorine in the pool. The opposite is closer to the truth. That sharp odor comes from chloramines, a form of combined chlorine that forms in the water when chlorine binds with contaminants such as sweat, urine, and other waste that swimmers carry in with them. Clean, well-maintained water has very little smell at all.

Once chloramines form, they do not stay put. They off gas into the air above the water, which is why the smell hangs over the surface and why it can bother people sitting poolside as well as swimmers in the water. So the sting in your eyes and that familiar smell are signs the water is working hard against waste, not signs of an overdose.

There is another cost worth knowing about. Chlorine that has been tied up in chloramines is chlorine that is no longer free to do its main job, which is killing germs. The more waste in the water, the less sanitizing power remains available, and the more the water depends on fresh chlorine being added to keep up. A stinging pool is asking for attention, and the fix starts with understanding what the smell really means.

Chloramines can get into the air

Chloramines do not only bother people in the water. When they come up out of a pool, they can turn into gas and mix with the air just above the surface. Swimmers breathing at that level can then feel irritation in the nose and breathing passages, on top of the skin and eye irritation the water itself can cause. This tends to matter most indoors, where the air over the pool has nowhere to go.

That air is only as clean as the water underneath it. If chloramines build up in the pool, they can build up in the air above it too, especially when there is not enough fresh air moving through the space. In a well ventilated indoor pool room, or outdoors where the air is open, this is less of a problem. The point is that the smell and stinging people notice around a pool often come from the air, and the way to fix the air starts with the water.

Checking the water

Good water habits start with regular testing. Check the disinfectant level, whether the pool runs on chlorine or bromine, along with the pH at least twice each day. When the pool sees heavy use, test even more often, since swimmers and their effects on the water can shift readings quickly. The goal is to keep both readings within the recommended levels.

Chlorine testing involves two separate numbers. One is the total chlorine in the water, and the other is the free chlorine, which is the portion still available to do its job.

The difference between the two numbers tells you how much combined chlorine is present. Subtract the free chlorine number from the total chlorine number, and what remains is combined chlorine, the part tied up with contaminants rather than working in the water. Tracking that gap over time gives a clearer picture of what is building up.

Keeping body waste out

A lot of what stings swimmers' eyes comes from what people carry into the water on their skin. Rinsing off in the shower for at least a minute before swimming washes away dirt and anything else sitting on the body, so less of it ends up in the pool. Even a quick rinse does real work, because it removes much of the body waste that goes on to form chloramines, the compounds behind that familiar eye irritation.

What happens in the water matters just as much. Peeing or pooping in the pool adds waste that the chlorine then has to fight, so it simply should not happen. Kids need help keeping the water clean, too. Take them on bathroom breaks and check their diapers about every hour, since a diaper held too long can leak without anyone noticing.

One more habit rounds this out: keep your mouth closed while you swim and avoid swallowing the water. Clean pools are a shared effort, and small habits add up quickly.

Next step: water testing and chemistry service.

Sources

• Centers for Disease Control and Prevention: Guidelines for Keeping Your Pool Safe and Healthy
• Centers for Disease Control and Prevention: Chloramines and Pool Operation

In Austin

Fill water matters here. Austin Water reported finished water leaving its three plants in the second quarter of 2026 at pH 9.65 to 9.74, total hardness of 76 to 77 mg/L as CaCO3, total alkalinity of 51 to 60 mg/L, and 2.52 to 2.69 mg/L of chloramines. Those are averages for tap water, not readings of your pool, so test the pool itself after a top-up.

Source: Austin Water, Water Quality Summary, 2nd Quarter 2026 (samples April 1 to June 30, 2026), finished water at the Davis, Ullrich and Handcox plant taps.

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Sullivan’s Pool Service maintains pools in and around Austin, including Northwest Hills, South Austin, West Lake Hills, Tarrytown, Great Hills, River Place, Crestview, East Austin, North Austin, West Campus, Hyde Park, Downtown Austin and St. Johns, and in Bee Cave, Cedar Park, Georgetown, Leander, Pflugerville and Round Rock. See every service area.

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