Key TakeawaysCryptosporidium is a common cause of waterborne diarrhea that can survive in well-maintained pools for over 10 days.The average adult swallows about one tablespoon of pool water per swim session, which can be enough to cause illness.Showering before swimming and avoiding the pool when sick are crucial practices to prevent the spread of germs and maintain pool hygiene.
Key Takeaways
Cryptosporidium is a common cause of waterborne diarrhea that can survive in well-maintained pools for over 10 days.The average adult swallows about one tablespoon of pool water per swim session, which can be enough to cause illness.Showering before swimming and avoiding the pool when sick are crucial practices to prevent the spread of germs and maintain pool hygiene.
Swimming pools can help you cool off in the summer heat wave, but some pools can be breeding grounds for parasites and bacteria that lead to diarrhea, rashes, respiratory illnesses, and ear infections.
On average, you can bring 10 million microbes into the pool just from your hair. Your hands can carry an additional 5 million microbes, and a single drop of spit can add another 8 million.
While not all microbes are harmful, some can cause illnesses.The average adult swallows about one tablespoon of pool water during a 45-minute swim session, which is “more than enough to make you sick,” according to the Centers for Disease Control and Prevention (CDC).
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Pools and water parks are treated with chemicals, such as chlorine and bromine, to kill most germs. But it’s a common misconception that swimming pools are a “sterile environment,” according toTrisha Robinson, MPH, an epidemiologist supervisor with the waterborne diseases unit at the Minnesota Department of Health.
Chlorine often fails to kill parasites like Cryptosporidium (crypto), she said, which can survive in a filtered and disinfected pool for more than 10 days. E. coli, giardia, and other germs can also contaminate the water, but crypto is the most common cause of waterborne diarrhea.
A crypto infection can take anywhere from two to 10 days for symptoms to appear. People may experiencewatery diarrhea, nausea, dehydration, and stomach cramping. Those with weakened immune systems may have a more serious, or even fatal, infection.
Common Recreational Water Illnesses and How to Prevent Them
How Can You Protect Yourself and Others?
If you’re infected with crypto, the parasite can stay in your body for up to two weeks. The CDC recommends staying out of the water for two weeks after your diarrhea has completely stopped.
Kelly Johnson-Arbor, MD, a medical toxicologist and co-medical director at the National Capital Poison Center, told Verywell that people might assume it’s fine to go swimming once their diarrhea stops, but they can still carry germs with them.
The CDC says most people always have a small amount of poop on their bodies. Even though this amount of fecal matter is equivalent to just “a few grains of sand,” it can wash off and contaminate the swimming water.
“If one person with Cryptosporidium gets into a pool, it can lead to days or even weeks of exposures for many, many people,” Johnson-Arbor said.
Showering for 60 seconds before getting in a pool could remove most of the unwanted substances from your skin, helping to preserve the chlorine or bromine that’s meant to kill germs.However,2019 surveyfound that only 31% of respondents shower before swimming.
Why Water Quality Testing Is ImportantAs chlorine combines with dirt and sweat, its disinfection power is greatly reduced.This is why chlorine levels must be maintained and tested regularly.In 2021, a 3-year-old died aftergetting infected with a brain-eating amoebaat a public splash pad in Texas.Health officials later found that the water was recirculated and there were gaps in water-quality testing. Although cases like these are extremely rare, infection with this amoeba can be fatal if it travels to the brain through the nose.
Why Water Quality Testing Is Important
As chlorine combines with dirt and sweat, its disinfection power is greatly reduced.This is why chlorine levels must be maintained and tested regularly.In 2021, a 3-year-old died aftergetting infected with a brain-eating amoebaat a public splash pad in Texas.Health officials later found that the water was recirculated and there were gaps in water-quality testing. Although cases like these are extremely rare, infection with this amoeba can be fatal if it travels to the brain through the nose.
As chlorine combines with dirt and sweat, its disinfection power is greatly reduced.This is why chlorine levels must be maintained and tested regularly.
In 2021, a 3-year-old died aftergetting infected with a brain-eating amoebaat a public splash pad in Texas.Health officials later found that the water was recirculated and there were gaps in water-quality testing. Although cases like these are extremely rare, infection with this amoeba can be fatal if it travels to the brain through the nose.
How Can You Tell If the Water Is Clean?
Pools, waterparks, and hot tubs are mainly disinfected with chlorine. When chlorine comes in contact with dirt, sweat, urine, and other contaminants, a strong-smelling substance called chloramine is formed.
“If you smell a strong odor of chlorine, it doesn’t mean that the pool is super clean, it means that there are a lot of germs coming off of peoples' bodies hanging out at the pool,” Johnson-Arbor said.
Chloramines can lead to skin, eye, and nose irritations,but moving to an area with fresh air can clear up these irritations for most people.
The Link Between Chlorine and Eczema
Public pools are routinely inspected for chlorination and pH balance. You can often find safety inspection records on your local health department’s website. For added caution, you can use over-the-counter test strips to check the water’s chlorine level before getting in.
If you have an open wound or a new tattoo, experts also say it’s best to avoid swimming pools until it’s healed.
Robinson emphasized that showering before entering a pool, staying out of the water if you’re sick, and keeping water out of your mouth as much as possible can minimize the risk of spreading germs.
“It’s not to scare people to stay out of the water or anything like that,” Robinson said. “Swimming is really great. People can have a lot of fun with it.”
What Is Chlorine Rash?
What This Means For YouTo keep swimming pools clean, always shower for at least 60 seconds before entering the pool. Refrain from swimming if you have been recently sick, especially with diarrhea. By following these precautions, you can enjoy swimming while protecting your health and that of others.
What This Means For You
To keep swimming pools clean, always shower for at least 60 seconds before entering the pool. Refrain from swimming if you have been recently sick, especially with diarrhea. By following these precautions, you can enjoy swimming while protecting your health and that of others.
13 SourcesVerywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.Centers for Disease Control and Prevention.Swimming-related illnesses.Centers for Disease Control and Prevention.Clean it up, swimmers.National Academies.Are all microbes dangerous?Centers for Disease Control and Prevention.Water treatment and testing.Yoder JS, Beach MJ.Cryptosporidium surveillance and risk factors in the United States.Experimental Parasitology. 2010;124(1):31-39. doi:10.1016/j.exppara.2009.09.020Centers for Disease Control and Prevention.Parasites- cryptosporidium (also known as “crypto”) - illnesses & symptoms.Centers for Disease Control and Prevention.Diarrhea and swimming.Water Quality and Health Council.Survey: 1 in 4 adults would swim with diahrrea.Wiant C, Vincent BG.A new survey reveals Americans’ understanding and misunderstanding of pool chemicals. Water Quality and Health Council. Published online May 24, 2019.Centers for Disease Control and Prevention.Splash pads.Centers for Disease Control and Prevention.Parasites — naegleria fowleri — primary amebic meningoencephalitis (PAM) — amebic encephalitis.Poison Control.What to know about pool chemical safety.Centers for Disease Control and Prevention.Chloramines and pool operation.
13 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.Centers for Disease Control and Prevention.Swimming-related illnesses.Centers for Disease Control and Prevention.Clean it up, swimmers.National Academies.Are all microbes dangerous?Centers for Disease Control and Prevention.Water treatment and testing.Yoder JS, Beach MJ.Cryptosporidium surveillance and risk factors in the United States.Experimental Parasitology. 2010;124(1):31-39. doi:10.1016/j.exppara.2009.09.020Centers for Disease Control and Prevention.Parasites- cryptosporidium (also known as “crypto”) - illnesses & symptoms.Centers for Disease Control and Prevention.Diarrhea and swimming.Water Quality and Health Council.Survey: 1 in 4 adults would swim with diahrrea.Wiant C, Vincent BG.A new survey reveals Americans’ understanding and misunderstanding of pool chemicals. Water Quality and Health Council. Published online May 24, 2019.Centers for Disease Control and Prevention.Splash pads.Centers for Disease Control and Prevention.Parasites — naegleria fowleri — primary amebic meningoencephalitis (PAM) — amebic encephalitis.Poison Control.What to know about pool chemical safety.Centers for Disease Control and Prevention.Chloramines and pool operation.
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
Centers for Disease Control and Prevention.Swimming-related illnesses.Centers for Disease Control and Prevention.Clean it up, swimmers.National Academies.Are all microbes dangerous?Centers for Disease Control and Prevention.Water treatment and testing.Yoder JS, Beach MJ.Cryptosporidium surveillance and risk factors in the United States.Experimental Parasitology. 2010;124(1):31-39. doi:10.1016/j.exppara.2009.09.020Centers for Disease Control and Prevention.Parasites- cryptosporidium (also known as “crypto”) - illnesses & symptoms.Centers for Disease Control and Prevention.Diarrhea and swimming.Water Quality and Health Council.Survey: 1 in 4 adults would swim with diahrrea.Wiant C, Vincent BG.A new survey reveals Americans’ understanding and misunderstanding of pool chemicals. Water Quality and Health Council. Published online May 24, 2019.Centers for Disease Control and Prevention.Splash pads.Centers for Disease Control and Prevention.Parasites — naegleria fowleri — primary amebic meningoencephalitis (PAM) — amebic encephalitis.Poison Control.What to know about pool chemical safety.Centers for Disease Control and Prevention.Chloramines and pool operation.
Centers for Disease Control and Prevention.Swimming-related illnesses.
Centers for Disease Control and Prevention.Clean it up, swimmers.
National Academies.Are all microbes dangerous?
Centers for Disease Control and Prevention.Water treatment and testing.
Yoder JS, Beach MJ.Cryptosporidium surveillance and risk factors in the United States.Experimental Parasitology. 2010;124(1):31-39. doi:10.1016/j.exppara.2009.09.020
Centers for Disease Control and Prevention.Parasites- cryptosporidium (also known as “crypto”) - illnesses & symptoms.
Centers for Disease Control and Prevention.Diarrhea and swimming.
Water Quality and Health Council.Survey: 1 in 4 adults would swim with diahrrea.
Wiant C, Vincent BG.A new survey reveals Americans’ understanding and misunderstanding of pool chemicals. Water Quality and Health Council. Published online May 24, 2019.
Centers for Disease Control and Prevention.Splash pads.
Centers for Disease Control and Prevention.Parasites — naegleria fowleri — primary amebic meningoencephalitis (PAM) — amebic encephalitis.
Poison Control.What to know about pool chemical safety.
Centers for Disease Control and Prevention.Chloramines and pool operation.
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