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Peeing in Swimming Pools: Urine, Chemicals, and Health Hazards

Swimming in a pool is fun, but the condition of the water is an important factor to consider.

Swimming in a pool is fun, but the condition of the water is an important factor to consider.

The Problem With Peeing in Pools

Many people reading this article wouldn't dream of peeing in a swimming pool. According to a report published in an American Chemical Society journal, however, it's happening often enough to create a health hazard in some pools. Members of the general public and elite swimmers alike have admitted to peeing during swims. Some elite swimmers urinate in pool water frequently. There is evidence that urine is also being released into hot tub water.

The main problem with peeing in a swimming pool or hot tub is not the release of bacteria. Although urine isn't sterile (despite a rumour to the contrary), it generally contains a low level of microbes unless a person has a urinary tract infection. In addition, the water in pools and tubs usually contains disinfectants that kill bacteria and other microbes. Unfortunately, chemicals in urine react with the disinfectants to create potentially harmful products.

Swimming is good exercise, especially when the pool environment is healthy.

Swimming is good exercise, especially when the pool environment is healthy.

Experimental Evidence for Urination in Pools

In a major investigation, researchers from the University of Alberta in Edmonton collected water samples from pools and hot tubs in two Canadian cities. They tested the urine for the presence of acesulfame potassium, also known as acesulfame K or ACE. The chemical is a common artificial sweetener in soft drinks and processed food. It's even used as an ingredient in other sugar substitutes. It passes through the body and into the urine without being altered.

The researchers tested a total of 250 water samples from 31 pools and hot tubs. They also tested 90 samples of the tap water used to fill the pools and tubs. They discovered that ACE was present in every sample that they tested. They also found that the chemical was up to 570 times more concentrated in the pool and hot tub water than in tap water. Since ACE is not deliberately added to swimming pools or hot tubs and is excreted in human urine, the investigators concluded that people had urinated in the water.

The reason why a small amount of acesulfame K was found in tap water is due to its stability. Some of the chemical survives wastewater treatment. It has been found in groundwater and enters tap water, although not in sufficient quantities to make the water taste sweet.

Lest readers get the impression that only Canadians like to pee in pools, it should be noted that peeing in swimming pools is common in elite U.S. swimmers, as mentioned in the video below.

Facts About Disinfection By-Products

Urine contains nitrogenous waste products, including urea, uric acid, ammonia, and creatinine. It has been known for some time that these react with chlorine-based disinfectants in pool water to form disinfection by-products, or DBPs. Bromine, ozone, and ultraviolet radiation are also used to disinfect the water, either on their own or in combination with another technique. This can cause the production of other by-products. This article discusses the effects of chlorine-based disinfectants, which are the most common type at the moment.

Hundreds of different DBPs can form in and around swimming pools, but some are more common than others. One researcher has said that he's found the same eleven volatile DBPs in every sample of swimming pool water that he's examined. The chemicals are produced not only from the components of urine but also from chemicals in sweat, personal care products, dirt, dead cells, and hair. In addition, they are made from the remains of medications that have entered the urine.

Swimming pools must contain disinfectants in order to prevent the transmission of disease. We have some control over the substances that enter the water from our bodies and from disinfectant by-products, however. I've chosen three common DBPs to discuss in this article–trichloramine, cyanogen chloride, and chloroform.

Disinfection by-products are present in treated tap water, including the water used to fill swimming pools. They make a relatively minor contribution to the DBP level in swimming pools, however. Most of the products in a pool are made after people have entered it and voluntarily or involuntarily released substances from their body.

Disinfection of Swimming Pool Water

Sodium hypochlorite and calcium hypochlorite are added to swimming pool water as disinfectants. Chlorine is used much less often because it's not as safe to store and apply. All three substances react with water to make hypochlorous acid, which kills bacteria.

Ammonia and related chemicals in sweat and urine react with hypochlorous acid. The reaction produces chemicals called chloramines. One of these chloramines is known as trichloramine. Trichloramine is responsible for the typical swimming pool smell, which is often wrongly attributed to chlorine.


Trichloramine has the chemical formula NCl3 and is also known as nitrogen trichloride. It's one of the most common and annoying disinfection by-products. The chemical can cause eye and skin irritation as well as respiratory problems, including asthma. This can be true even when the chemical is at usual pool concentrations and gets worse as the concentration increases.

Although DBPs are often dangerous when they are in a concentrated form, they are safer at the low concentrations present in swimming pools. Pure trichloramine is an explosive substance. Fortunately, this isn't true for the chemical when it's present in pool water.

Even a residential pool requires some form of disinfection.

Even a residential pool requires some form of disinfection.

Cyanogen Chloride

Cyanogen chloride or CNCl is another common disinfection by-product. It can be deadly when it's concentrated. Like other DBPs, it has a relatively low concentration in and around pool water. People don't drop dead after inhaling or swallowing it when they visit a swimming pool. Nevertheless, the chemical is of concern.

Like trichloramine, cyanogen chloride is a volatile substance (one that readily turns into a gas). The concentrated chemical causes severe irritation of the eyes, skin, and airways and interferes with the body's ability to use oxygen. It can also cause fluid buildup in the lungs (edema), convulsions, loss of consciousness, and death. The chemical is highly unlikely to be sufficiently concentrated in swimming pool water to cause serious effects, though.

It's uncertain whether DBPs in pool water are sufficiently concentrated to cause any serious health effects. There are preliminary indications that some of them may be, but the discoveries need to be confirmed.


Chloroform or CHCl3 is yet another common DBP. Once again, it's a volatile chemical that is normally present at a low concentration in and around swimming pools but is of some concern.

The concentrated chemical irritates the eyes and skin. It also depresses the activity of the central nervous system and can cause a coma. It was once used as an anesthetic. It was found to be dangerous because it can trigger a deadly alteration in the rhythm of the heartbeat. Doctors also found it hard to control the dose. Concentrated chloroform inhaled over a long period damages the liver and kidneys. The chemical is a suspected carcinogen (a substance that causes cancer).

Keeping a pool as safe as possible is important for everyone.

Keeping a pool as safe as possible is important for everyone.

Swim diapers and swim pants are not a substitute for frequent diaper changing and bathroom breaks. It is recommended that swim diapers and swim pants are checked frequently and changed away from the poolside.

— Centers for Disease Control and Prevention (CDC)

Public Health Recommendations

Swimming in a pool is fun and can be great exercise. It's not necessary to avoid the fun or the exercise unless the disinfection by-products are too irritating for a swim or unless the pool maintenance program is of concern. I think that it's the responsibility of swimmers to follow public health recommendations, however, for the sake of themselves and of other swimmers. Many of these recommendations are listed below.

  • Shower with soap before entering a pool to remove sweat, personal care products, dead cells, and fecal matter from the skin. Feces can transmit disease.
  • Don't enter the water if you have diarrhea, an intestinal infection, or a urinary tract infection. Small quantities of feces and urine can be released into the water accidentally.
  • Don't swallow pool water and try to avoid getting it in your mouth.
  • Make sure that indoor pools have good air circulation, since many DBPs are volatile and enter the air as a gas.
  • Use the restroom whenever the urge to pee appears.
  • Make sure that children urinate in the restroom before entering the water and that they leave the water whenever they need to "go".
  • If children mention peeing in the pool, explain that this action is not a game and that it can affect the health of other people.
  • Make sure that babies wear good swim diapers. These retain solid feces, but unfortunately they may not retain liquids. In addition, they don't prevent harmful microbes in diarrhea from contaminating the water. They should be inspected and changed frequently.
  • Shower after a swim to remove contaminants.

Untreated water can accumulate harmful Escherichia coli and Salmonella bacteria and protozoans such as Cryptosporidium parvum and Giardia lamblia.

— Chemical and Engineering News Magazine

Managing Pool Water

Pool managers have a difficult but very important task. They must add enough disinfectant to the water to kill microbes and keep people safe but not so much that disinfection by-products become dangerous. The choice of disinfectant is also important. Chlorine, sodium hypochlorite, and calcium hypochlorite disinfectants form hypochlorous acid in water, which destroys many pathogens (microbes that cause disease). Chlorine-based disinfectants are sometimes combined with another type to ensure that a wide range of microbes are suppressed for as long as possible and with as few side effects as possible.

A small amount of new water is generally added to a pool every day in order to replace the water lost by evaporation and other activities. The American Chemical Society says that it takes about a hundred days to completely replace the water in an average swimming pool. This give DBPs time to accumulate.

The public can help the situation by reducing their contribution to by-product production. Some production of the chemicals is inevitable, since we release urea in our perspiration as we exercise. By avoiding voluntary urine release we can keep the pool environment healthier and more pleasant for everyone, however. This should enable us to continue enjoying fun and exercise in swimming pools without experiencing any unnecessary problems.


  • A method to monitor urine in pools from the news service
  • The Chemistry of Swimming Pools from Compound Interest (This is the pen name of a chemistry teacher and graphics creator named Andy Brunning.)
  • Information about swim diapers and swim pants from the CDC (Centers for Disease Control and Prevention) This site also has other tips about swimming pool safety.

This content is accurate and true to the best of the author’s knowledge and does not substitute for diagnosis, prognosis, treatment, prescription, and/or dietary advice from a licensed health professional. Drugs, supplements, and natural remedies may have dangerous side effects. If pregnant or nursing, consult with a qualified provider on an individual basis. Seek immediate help if you are experiencing a medical emergency.

© 2017 Linda Crampton


Linda Crampton (author) from British Columbia, Canada on January 14, 2018:

Thank you very much for the kind comment, Jorge!

Jorge Cruz from Canada on January 14, 2018:

As a swimmer that never pees in the pool, I greatly appreciate your article. I wish it was posted on every swimming pool board.

Linda Crampton (author) from British Columbia, Canada on November 13, 2017:

I spent quite a lot of time in swimming pools when I was a child, but I haven't been in one for some time. I'm kind of glad! Thanks for the visit, Peg.

Peg Cole from North Dallas, Texas on November 13, 2017:

Good to know that urine can be detected in pools. We grew up in Florida and spent countless hours swimming in public pools and later in a small pool at our house. Thankfully, the cabana opened directly onto the pool deck so it was convenient to go inside whenever necessary. I don't think I'll be swimming in public pools again. Eeewwww.

Linda Crampton (author) from British Columbia, Canada on March 31, 2017:

I know the feeling, Thelma. It is very tempting to swim in pools! Thanks for the comment.

Thelma Alberts from Germany on March 31, 2017:

That is the reason why I hesitate to swim in the pool. I know that kids and maybe adults urinate in the pools. It is just yucky but sometimes I can't resist to swim in the pool. Thanks for sharing this very informative hub Linda.

Linda Crampton (author) from British Columbia, Canada on March 25, 2017:

Thank you very much for the visit and the comment, Manatita.

Manatita44 on March 25, 2017:

An interesting one and something that I wouldn't normally think of. Excellent piece and great value advice towards the end.

Linda Crampton (author) from British Columbia, Canada on March 18, 2017:

Hi, Nell. Yes, the chemicals and materials that are often present in swimming pools are definitely something to think about. I think that their possible effects are important to consider.

Nell Rose from England on March 18, 2017:

I must admit I had thought about the dangers before, but didn't have a clue what the chemicals were! yuck basically! lol! great info though and something I will take care of when going swimming again.

Linda Crampton (author) from British Columbia, Canada on March 14, 2017:

I like that story, Leonard! It sounds like a great strategy to stop young children from peeing in pools. I appreciate your comment.

Leonard Tillerman from Toronto, Canada on March 14, 2017:

Thank you for a great article outlining the very real health risks. I remember when I was a child that one of my friend's parents said that they put a chemical in the pool which interacted with urine in such a way it gave off a distinct colour. That made it so nobody ever wanted to pee in their pool!

Linda Crampton (author) from British Columbia, Canada on March 10, 2017:

Hi, Genna. Swimming pools can offer a lot of fun. I think it's great that your grandchildren take swimming lessons and that they enjoy them. I hope the school is taking precautions related to water safety. I expect they are.

Genna East from Massachusetts, USA on March 10, 2017:

You've written another interesting hub, Linda. The word, "gross," comes to mind whenever I think of someone peeing in a pool. I have to admit I was disappointed to learn that Phelps, and others pee in the water. My grandchildren take swimming lessons. My granddaughter likes the water; my grandson loves it. (He's part fish. :-) I sometimes wonder if the school's management is taking all of the precautionary measures. It can be more challenging for youngsters to control their bladders while in the water. They all take showers when done, so I try not to worry.

Linda Crampton (author) from British Columbia, Canada on March 09, 2017:

Hi, Vellur. I agree with all your points. The elite swimmers say that it interferes with their training when they have to leave the water to use the restroom. I wonder how many of them realize that they're altering the chemistry of the pool water, though. The reaction of urine with disinfectant increases the risk of asthma attacks in susceptible swimmers.

Nithya Venkat from Dubai on March 09, 2017:

Elite swimmers peeing in the pool is appalling. There are restrooms, and they just have to use it. Parents should also tell their children not to pee in the pool. Thank you for sharing this article.

Linda Crampton (author) from British Columbia, Canada on March 08, 2017:

Hi, Jackie. Yes, I think a person need to choose a pool carefully if they want to swim in one. I certainly understand your point of view!

Jackie Lynnley on March 08, 2017:

Like FA I swore off pools years ago finding out this was happening. Just grossed me out too much to be able to enjoy it anytime.

Great info!

Linda Crampton (author) from British Columbia, Canada on March 07, 2017:

It seems like a lot of people have done it, at least when they were children!

Larry Rankin from Oklahoma on March 07, 2017:

As a kid I've done it. Most folks have if they're honest.

Very interesting to see some of the real world consequences to this dirty little secret.

Linda Crampton (author) from British Columbia, Canada on March 07, 2017:

Hi, MsDora. Yes, peeing in the ocean or in other bodies of water in nature is another important topic to consider. Thanks for the visit.

Dora Weithers from The Caribbean on March 07, 2017:

Haven't been in a pool in years, but I worry about how much similar hazards can affect us in the ocean. People swimming right next to each other pee without even thinking of moving away. Thanks for making us aware of these health hazards which we can definitely do without.

Linda Crampton (author) from British Columbia, Canada on March 07, 2017:

Thank you very much for the comment, RTalloni. I appreciate your visit a great deal.

RTalloni on March 07, 2017:

As always, very interesting…and amazing on so many levels! Thanks for highlighting the issues related to these pool health hazards!

Linda Crampton (author) from British Columbia, Canada on March 06, 2017:

I can understand your decision, Suhail! I appreciate your visit and comment.

Suhail Zubaid aka Clark Kent from Mississauga, ON on March 06, 2017:


Thanks for writing a very informative article like this one. It is because of this hazard that I stopped going to the swimming pools ha-ha.

I only swim in rivers now ha-ha.

Linda Crampton (author) from British Columbia, Canada on March 06, 2017:

Don't worry, Mel—I knew that you were joking! I love your sense of humour. Thanks for the second comment.

Mel Carriere from Snowbound and down in Northern Colorado on March 06, 2017:

I hope you know I meant that Canadians comment tongue in cheek Linda. I never knew that Canadians had a reputation for peeing in pools. I assumed all the swimming pools in Canada were frozen over, and they used them for hockey rinks. Love your articles.

Linda Crampton (author) from British Columbia, Canada on March 06, 2017:

Thank you, Martie. It's a great shame when people spoil a public area for others. Swimmers should be able to enter a pool without worrying about what's in the water.

Martie Coetser from South Africa on March 06, 2017:

This is the most disgusting aspect about a pool. Whenever I enter one, the knowledge that people have peed in it repels me.

Thanks for another very informative hub, Alicia. Interesting to know that the typical smell of a pool comes from Trichloramine and not Chlorine.

Linda Crampton (author) from British Columbia, Canada on March 06, 2017:

I love your friend's sign, Mel. Unfortunately, far more people than Canadians seem to be peeing in swimming pools. It would be interesting to do a survey by country, although I think many people might be embarrassed to admit that they pee in pools. I appreciate your comment.

Linda Crampton (author) from British Columbia, Canada on March 06, 2017:

Hi, Bill. I know what you mean about feeling disgusted! Thank you once again for visiting and commenting.

Mel Carriere from Snowbound and down in Northern Colorado on March 06, 2017:

A friend of mine had a sign over his pool that said "Please do not pee in our pool, we don't swim in your toilet." I think that pretty much sums it up.

I thought it was only those crazy Canadians peeing in pools. I'm certainly glad you set the record straight on that one. Those self-entitled bad boy Olympic gold medal swimmers are ruining things for everyone.

I like your new profile picture, by the way. Great hub! Once again you introduce me to ideas I wasn't even thinking about.

Bill Holland from Olympia, WA on March 06, 2017:

Okay, I'm thoroughly disgusted now, thank you very much, and yet what kid can truthfully say he/she hasn't peed in a pool? I'm just glad I finally grew up.

Linda Crampton (author) from British Columbia, Canada on March 06, 2017:

What an interesting and gross story, Flourish. I can definitely understand your feelings about swimming pools after your experience. I suspect that I'll be thinking about the scene that you describe for the rest of the day!

Linda Crampton (author) from British Columbia, Canada on March 06, 2017:

Hi, Jodah. Yes, the swimmers aren't setting a very good example for the rest of us! Thanks for the comment.

Linda Crampton (author) from British Columbia, Canada on March 06, 2017:

Hi, Buildreps. I can understand why children may think it's funny to pee in a pool (although I hope someone tells them that it's not a good idea), but as you say, it's not nice to think of adults doing this! Thanks for the visit.

FlourishAnyway from USA on March 06, 2017:

You just confirmed my germaphobe memories as not an isolated incident. The last time we took our daughter to an indoor water slide hotel and adventure park was about 10 years ago. I became pretty grossed out seeing a baby with a soiled diaper coming out of the pool and another child purposely urinating right through her bathing suit on the fountains (she told her friends she was washing off). Between that and the ripped off bandaids I've never been back. I don't swim anymore because of what I saw, not at the YMCA or my homeowners association pool. People are gross. If I owned a pool I'd have no problem doing so. I would probably have to tell people that I've installed a special technology that spotlights pissers.

John Hansen from Australia (Gondwana Land) on March 06, 2017:

Well, this was a very informative and somewhat concerning article, Linda. I never imagined that elite swimmers would consider it normal and ok to pee in the pool. Great job on researching this.

Buildreps from Europe on March 06, 2017:

Interesting to read. I didn't knew so many chemicals are formed. I must admit, as a child once in a while I peed in the swimming pool. I think it's very dirty especially when adults do this. Yeck! Thanks for this nice article.

Linda Crampton (author) from British Columbia, Canada on March 05, 2017:

Thanks for commenting and for sharing the interesting information, MsLizzy. Some forms of disinfection do avoid the smell. The chlorine-based methods seems to be the most common at the moment, though. I hope other methods such as the ones that you mention become more popular, as long as they work well.

Linda Crampton (author) from British Columbia, Canada on March 05, 2017:

Hi, Peggy. I think it's sad that people relieve themselves in pool water, too, although according to what I've read some people think there's nothing wrong with it. They might change their mind if they knew what was happening chemically! Thanks for the comment.

Liz Elias from Oakley, CA on March 05, 2017:

Most interesting, and informative. I suppose all of us, at one time or another are guilty of this as children. I was shocked at the number of adults also guilty. The only time I have ever allowed that to happen, as an adult, is when I was swimming in a river. (The fish and other residents do it all the time, after all. :-) ) The area of the boat containing the 'head' (potty, to landlubbers), was carpeted, and you don't want soggy carpet on a boat, as it can lead to mold and mildew.

Recently, however, I've read about a whole different type of swimming pool disinfection that uses some other process, and you don't get that awful "swimming pool smell." I forget what it's called, but it's an oxygenation or some such bases system. And then, there are salt water pools, and I don't think those use chlorine, either. But I'm not sure; we don't have a pool.

Peggy Woods from Houston, Texas on March 05, 2017:

Very important information to share with others. It is sad to think that some people relieve themselves in pool waters instead of using a nearby restroom. This should definitely be a wake up call! Thanks for researching and writing this.