Why Do My Eyes Sting After Swimming in My Pool?
Stinging eyes almost never mean too much chlorine. Here's how to tell whether pH or combined chlorine (chloramines) is the real cause, and what to do about each.
You get out of the pool, your eyes are red and stinging, and the obvious explanation seems to be that there's too much chlorine in the water. It's a reasonable guess, and it's almost always the wrong one. Stinging eyes are usually a sign of a chemistry imbalance, but it's rarely the chlorine level itself. This is common enough that most pool owners run into it at some point, and it's rarely a sign of anything seriously wrong. Here's what's actually going on and how to fix it.
It's usually not "too much chlorine"
Properly balanced pool water with plenty of free chlorine in it doesn't have much smell at all, and it shouldn't sting healthy eyes. That strong "chlorine smell" people associate with pools, the one that makes eyes burn and throats feel tight, is actually the smell of combined chlorine, also called chloramines. Chloramines form when free chlorine reacts with things bathers bring into the water: sweat, body oils, sunscreen, and urine. Once chlorine has bonded with those contaminants, it's used up and can't sanitize anymore, but it lingers as an irritating byproduct. So a pool that smells strongly of "chlorine" and stings your eyes usually needs more sanitizing capacity, not less.
The two usual suspects: pH and combined chlorine
| Parameter | Ideal range | Acceptable range |
|---|---|---|
| pH | 7.4-7.6 | 7.2-7.8 |
| Free chlorine | 1-3 ppm | 1-4 ppm |
| Combined chlorine | 0 ppm | 0-0.5 ppm |
Human tears sit at a pH close to 7.4, which is why the ideal pool pH range lands right around there too. When pool water drifts outside roughly 7.2 to 7.8, whether too acidic or too alkaline, it stops matching your eyes' natural chemistry and the mismatch stings, sometimes within minutes of getting in. This is why a pool with a low chlorine reading can still feel comfortable to swim in, and a pool with textbook chlorine levels can sting badly if the pH has drifted. Combined chlorine works differently: it's less about matching your body's chemistry and more about direct irritation from the chloramine compounds themselves, which is also why it tends to get worse in indoor pools where there's less air circulation to carry the fumes away.
Note: Stinging eyes don't automatically mean your pool is dirty or unsafe. It usually just means one of two common, fixable numbers has drifted, and most home pools only build up meaningful combined chlorine after a while without a shock treatment, not overnight.
How to fix it
- Test before you adjust anything. A basic test strip covers pH and free chlorine; a liquid kit or test strip that reports total chlorine lets you calculate combined chlorine (total chlorine minus free chlorine). Skimmer logs all of these together so you can see the trend, not just a single reading.
- If pH is outside 7.2-7.8, correct that first with a pH increaser or decreaser sized to your pool's volume with a pH calculator, then wait a few hours and retest. Getting pH back into range often resolves stinging on its own, even before you touch the chlorine.
- If combined chlorine is above 0.5 ppm, shock the pool. The standard rule of thumb is to dose roughly 10 times the combined chlorine reading in ppm of free chlorine, with a sensible minimum shock dose of about 10 ppm even when the reading is low. This is an estimate: actual results vary by product concentration and total alkalinity, so retest after dosing. Skimmer's chlorine calculator can work out the exact amount of liquid chlorine or cal-hypo for your pool's gallonage.
- Stay out of the water until the free chlorine level has settled back down into the normal 1-4 ppm range, following the wait time on your shock product's label. Sunlight burns off chlorine gradually, so this can take anywhere from a few hours to overnight depending on the dose and how much sun the pool gets.
- For prevention, encourage a quick rinse-off before swimming and keep up with a regular testing rhythm. Most combined chlorine buildups happen gradually over weeks of bather load, not from a single swim, so catching the trend early with weekly tests keeps it from becoming a stinging-eyes problem in the first place.
Quick relief while you get the chemistry right
None of this happens instantly. Correcting pH or clearing out combined chlorine can take a few hours to fully resolve, so it helps to know what actually eases the sting in the meantime. Rinsing your eyes with clean, fresh water as soon as you get out clears away the mismatch faster than just waiting it out. Swim goggles sidestep the problem entirely and are worth keeping poolside if anyone in the household likes to swim with their eyes open underwater. Over-the-counter artificial tears can also help if eyes stay irritated for a while after swimming, since they dilute and flush the surface of the eye. None of these fixes the underlying chemistry, though, so treat them as comfort measures while you test and correct the water, not a substitute for doing so.
Frequently asked
The water looks clear and doesn't smell strong, so why do my eyes still sting?
Does a strong chlorine smell mean there's too much chlorine in my pool?
How long do I need to stay out of the pool after shocking it?
Could this be a contact lens or allergy issue instead of the pool water?
Can high cyanuric acid make eye irritation worse?
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