Pool care articles
Why does my pool smell strongly of chlorine?
A strong chlorine smell over a pool can come from chloramines, which form when chlorine binds to the body waste swimmers bring into the water. The CDC lists their distinctive odor, along with eye, skin and breathing irritation, as a sign to watch for. Smell does not measure them, so test total and free chlorine and subtract free from total. Sullivan's Pool Service tests free and total chlorine on its weekly visits in Austin.
If you own a pool in Austin, in a neighborhood like South Austin or Northwest Hills, a strong chlorine smell over the water is a sign worth taking seriously. When chlorine binds to the body waste swimmers carry into the water, it can form chemicals called chloramines. Chloramines are a type of combined chlorine. When they off gas from the water into the air above it, they can irritate skin, eyes, and the respiratory tract, including the nose. The CDC lists that irritation and the distinctive odor in the swimming area as things to be on alert for, along with poop in the water.
Why the smell builds up
Chloramines that off gas are heavier than air, so they settle on top of the water's surface, where they can affect the people around it. They can build up in the air when there is not enough fresh air moving around the pool. The CDC says this is particularly true indoors.
The CDC names what causes chloramines to accumulate in the air above a pool. One is disturbing the water's surface, such as when swimmers move through the water or water is sprayed through features. Another is limiting the movement of fresh air over the surface.
How to check for chloramines
Testing is where a backyard owner can act directly. The arithmetic is simple. Measure total chlorine, measure free chlorine, and subtract the free chlorine number from the total chlorine number. Combined chlorine equals total chlorine minus free chlorine. Most city, county, and state health departments limit combined chlorine in water to 0.4 ppm or less.
Routine testing at home
For routine checks at home, the CDC's residential guidance recommends testing chlorine concentration and pH at least twice per day, and more often when the pool is being used by a number of people. A DPD test kit gives the most accurate results for chlorine and pH. Test strips can also be used, though they are less accurate than a DPD test kit, and you should always follow the manufacturer's directions. The CDC recommends a pH between 7.0 and 7.8, and a chlorine concentration of at least 1 ppm in pools, or at least 2 ppm if you use cyanuric acid or chlorine products containing it. The CDC also notes that chlorine disinfection takes longer when cyanuric acid is present, and recommends against cyanuric acid and stabilized chlorine in hot tubs.
Keeping chloramines down
Prevention starts before anyone gets in. Pee, poop, sweat, and dirt from swimmers' bodies are among the things the CDC lists as reducing chlorine concentration, and they are also what chlorine binds to when chloramines form. Stay out of the water with diarrhea, use the toilet before getting in, and never pee or poop in the water. Swimmers should rinse off before getting in; even a quick rinse shower removes much of the body waste that helps form chloramines.
Austin tap water and a top-up
Austin Water's quarterly table lists total chloramines in the finished tap water of 2.69 mg/L at Davis, 2.52 mg/L at Ullrich and 2.60 mg/L at Handcox. Chloramines are a type of combined chlorine. Those figures are averages for tap water, not readings of your pool, so test the pool itself.
Your part
The CDC states that as a residential pool or hot tub owner, it is your responsibility to regularly check the chlorine concentration and pH of the water to help protect users from swimming related illness, since chlorine and pH are the first defense against germs that can make swimmers sick. The combined chlorine calculation tells you where your water stands. And if the readings keep puzzling you, Sullivan's tests chlorine, pH, alkalinity, calcium hardness and stabilizer for pool owners across the city, doses corrections on site and writes down what was added.
Sources
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.
Related articles
- What is combined chlorine and how to measure it
- How fast does chlorine kill pool germs?
- How often should I test my pool in Austin?
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.
Weekly residential service has one fixed monthly price, set by pool size: see pool service pricing for what each size tier covers.
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