Yes, peeing in the pool causes problems. Urine on its own is fairly harmless. When it mixes with chlorine, compounds in pee such as uric acid react to form disinfection byproducts, including cyanogen chloride and trichloramine, that can irritate the eyes and lungs. A 2014 Purdue University study found that uric acid is an efficient source of both compounds, and the researchers estimated that more than 90% of the uric acid in pools comes from human urine.
The fix is simple: use the restroom before you swim.
How common is peeing in the pool?
Surveys and lab tests both suggest it is common. In a 2009 Water Quality & Health Council survey of 1,000 U.S. adults, one in five admitted to peeing in a swimming pool. In the council’s 2019 Healthy Pools survey, 40% of Americans said they had peed in a pool as an adult. The Water Quality & Health Council advises the chlorine industry’s trade association, so treat these as self-reported survey results.
Researchers have also measured it directly. A 2017 University of Alberta study published in Environmental Science & Technology Letters tracked an artificial sweetener that passes through the body unchanged. Across 29 pools in two Canadian cities, the team estimated that swimmers added about 75 liters (about 20 gallons) of urine to one 830,000-liter pool (about 220,000 gallons) over three weeks, and about 30 liters to a 420,000-liter pool.
What happens when pee mixes with pool chlorine?
Chlorine reacts with the nitrogen compounds in pee. The 2014 Purdue study, by Lushi Lian, Yue E, Jing Li and Ernest Blatchley III in Environmental Science & Technology, found that uric acid from urine reacts with chlorine to form two volatile byproducts:
- Cyanogen chloride (CNCl): a toxic compound that, when inhaled, can affect the lungs, heart and central nervous system.
- Trichloramine (NCl3): a chloramine that has been associated with acute lung injury in people exposed to chlorine-based disinfectants.
Both compounds can escape into the air above the water, which is why indoor pools with heavy use and poor ventilation tend to have the most irritating air. Blatchley said swimmers should adopt improved hygiene habits, since keeping urine out of pools would benefit both pool water and air chemistry.
Why does pee in the pool make your eyes red?
Red, itchy eyes at the pool usually come from chloramines. The CDC’s page on preventing eye irritation from pool chemicals explains that chlorine combines with sweat, pee and other material from swimmers to form chloramines, and chloramines can turn into gas and irritate the eyes and lungs. The same reaction is behind the strong “chlorine” smell at a busy indoor pool. Read more about what causes pool chlorine smell and how to get rid of it.
Can pool byproducts damage your DNA?
One small study looked at this question. In a 2010 study in Environmental Health Perspectives (Kogevinas and colleagues), 49 healthy adults swam for 40 minutes in an indoor chlorinated pool in Barcelona. Some markers of genetic damage rose with higher levels of certain byproducts, while other markers did not change. The study measured pool byproducts in general, not urine alone, and the authors asked for larger studies to confirm the results. For more on this research, see Can Pool Disinfection Byproducts Raise Your Cancer Risk?
How do you keep pee out of the pool?
CDC’s healthy swimming guidance gives swimmers and parents these steps:
- Use the restroom before swimming and never pee in the water.
- Take kids on bathroom breaks every hour, as recommended in CDC’s tips for keeping kids healthy at the pool.
- Change diapers in a diaper-changing area, away from the poolside.
- Shower before you get in. Rinsing off removes sweat and other material that also forms chloramines. Read about pool etiquette and showering in the U.S. and Europe.
- Wear a bathing cap and tell the lifeguard or pool operator about strong chemical smells.
For more swimmer safety tips, see how to practice safe and healthy swimming.
What can pool owners do about urine and chloramines?
Pool owners and operators can limit the byproducts that urine and sweat create. The CDC’s chloramine guidance for pool operators recommends measuring combined chlorine (total chlorine minus free chlorine), superchlorinating when combined chlorine is too high, moving fresh air across the water’s surface at indoor pools, posting swimmer hygiene rules in locker rooms, and using supplemental systems such as UV or ozone that break down chloramines.
Clear Comfort’s hydroxyl-based AOP is a supplemental system that destroys contaminants in the water so a pool can run low-chlorine. Hydroxyl-based AOP still works alongside a low chlorine residual: in residential pools, the typical free chlorine range with hydroxyl-based AOP is 0.5 to 1.5 ppm. Learn how hydroxyl-based AOP technology works.
Frequently asked questions
Does chlorine kill pee in the pool?
Chlorine reacts with the compounds in pee, and that reaction forms byproducts such as chloramines, trichloramine and cyanogen chloride, according to CDC and a 2014 Purdue study. Pee stays a problem even in a well-chlorinated pool. Keeping it out of the water is the best way to prevent those byproducts.
Is peeing in the pool harmful to swimmers?
Pee in the pool can cause red, itchy eyes and irritated lungs because it reacts with chlorine to form chloramines and other byproducts. A 2014 Purdue study found uric acid from urine forms cyanogen chloride and trichloramine, two compounds linked to lung and other health effects. Busy indoor pools with poor ventilation are where these byproducts build up most.
How much pee is in a public pool?
A 2017 University of Alberta study estimated about 75 liters (about 20 gallons) of urine in one 830,000-liter commercial pool over three weeks. The team measured an artificial sweetener that passes through the body unchanged across 29 pools in two Canadian cities. The amount depends on the pool’s size and how many people use it.
Why does a crowded pool smell stronger?
More swimmers bring more sweat and pee into the water, and chlorine reacts with them to form chloramines. CDC says chloramines can turn into gas, and the gas settles just above the water, especially at indoor pools. A strong “chlorine” smell usually means chloramines are building up.
How often should kids take bathroom breaks while swimming?
CDC recommends taking kids on bathroom breaks every hour. Change diapers in a diaper-changing area away from the pool, and have everyone use the restroom and shower before getting in. These steps keep pee and other material out of the water.
Want a low-chlorine pool at home? See how Clear Comfort works for residential pools and spas.
