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12 Ways Your Swimming Pool Is Making You Sick

There have been 500 illness outbreaks related to treated pool water in the last 15 years—yuck! Here's how to ensure you stay safe this summer season.

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Yellow noodle in the swimming pool outdoor

Your pool could be making you sick

If you’ve ever been sick after swimming, it may have been due to contaminated pool water. According to a 2018 report from the Centers for Disease Control and Prevention (CDC), more than 27,000 people have gotten sick from pools, hot tubs, and splash pads. Luckily, there are precautions you can take to make sure you don’t add yourself to that number. If you have a pool, it all starts with your water source. Here are 17 things you need to know about tap water—and whether yours is safe.

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Girl standing on diving board, preparing to dive

Most pools are safe

Yes, there could be something lurking in the water and the threat of illness is real, but overall your favorite local swimming pool is probably safe. “As long as the pH and chlorine levels in the pool are being maintained, the disinfectants will kill off most germs that could make you ill,” says Dan DeSimone, MD, infectious disease consultant at Mayo Clinic in Rochester, Minnesota. The Water Quality & Health Council, an independent, multidisciplinary group sponsored by the industry trade association the Chlorine Chemistry Division of the American Chemistry Council, has compiled a list of local and state health departments that can help you find public swimming pool inspection reports to ensure your local pool is in good health.

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Stair swimming pool in hotel pool resort.
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“Crypto” is a problem

Unfortunately, one germ, called Cryptosporidium, is fairly resistant to pool chemicals. “It’s the most common cause of diarrhea,” says Dr. DeSimone. It’s found in the fecal matter of fellow swimmers who are infected, and the spores can survive for hours to days in the water, he adds. The bug is nasty—it can cause diarrhea for up to two weeks, points out the CDC. To lower your risk, don’t swallow pool water (even small amounts). It shouldn’t have to be said, infants still in diapers shouldn’t be paddling in the big pool and anyone with diarrhea should avoid swimming.

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Happy young boy swim and dive underwater, kid breast stroke with fun in pool. Active healthy lifestyle, water sport activity and lessons with parents on summer family vacation with child.
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Your eyes aren’t red from the chlorine…

It’s easy to assume that it’s the chlorine that’s irritating your eyes. However, it’s actually the result of pool chemicals mixing with things like urine, sweat, and dirt, explains Chris Wiant, MPH, PhD, chair of the Water Quality & Health Council. “This is the chlorine doing its job,” he says. However, this process also uses up the disinfectant and creates strong-smelling compounds called chloramines—which are the source of that strong “chlorine smell.” If that smell is especially pungent, it’s a tip-off that the pool chemistry is off and needs to be looked at and possibly adjusted.

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Swim competition swimmer athlete doing crawl stroke in swimming pool. Sports man male swimmer with goggles and cap breathing racing in indoor stadium. Speed exercise workout.

Swimmer’s ear is for real

Itchiness, redness, swelling, and pain are the signs and symptoms of swimmer’s ear, an infection of the outer ear canal. It’s spread when water and pool bacteria get trapped in the ear canal and proliferate, says the CDC. Avoid swimmer’s ear by keeping ears blocked with earplugs or using a dry towel to wipe away moisture after swimming. If you get swimmer’s ear, your doctor may recommend ear drops that stop bacteria growth.

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Beautiful girl relaxing in jacuzzi. Summer vacation

That rash could be from the hot tub

While a soak in the hot tub may sound relaxing, you can end up with a skin infection caused by the bacteria Pseudomonas aeruginosa, a.k.a. hot tub rash. “The germ lives in water and thrives in a hot tub,” says Dr. DeSimone. Usually, the rash—which is itchy, bumpy, red, and sometimes pus-filled—goes away on its own, he says. The best way to avoid infection is to suds up with soap in the shower after every hot tub session, clean your swimsuit, and make sure that the hot tub you use is being properly maintained, says the CDC.

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Bright multicolor beach ball floating in blue swimming pool, colorful float in a refreshing blue swimming pool with waves reflecting in the summer sun. Active vacation background. Lifesaver for kid.
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Food poisoning from a pool?

Another icky problem caused by fecal contamination? E. coli. Nearly 60 percent of public pools were positive for the bacteria, according to a 2013 study from the CDC. The bright spot is that most E. coli are harmless, and none of the samples collected were the strain that causes illness. Nonetheless, this is evidence that the strains that can make you very ill with stomach cramps and diarrhea can survive in a pool. If you get sick within one or two days of swimming, there’s a good chance the pool is to blame, says Dr. DeSimone. Don’t miss these foods that have natural antibacterial properties.

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Vacation. Woman in a swimming pool

Yes, even Legionnaires’ disease

Bacteria called Legionella causes Legionnaires’ disease, a severe type of pneumonia, as well as Pontiac fever, a milder respiratory infection. According to CDC data, of the 27,000 cases of illness traced to pools, 16 percent were attributed to Legionella. Nine in 10 outbreaks could have been prevented with smart water cleaning practices, another reason you shouldn’t be shy about asking your local pool to show you an inspection report. Alert your doctor if you experience symptoms of Legionnaires’, which appear two to 10 days after infection and may include a headache, muscle pain, chills, and a potentially high fever.

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Hepatitis A is possible

Liver problems… from a pool? It’s rare but possible: The hepatitis A virus, which causes liver disease, can live in water and food contaminated by feces. And if you were to inadvertently take a gulp of the water, it could enter your system. While outbreaks happen, they’re rarely linked to recreational water like public pools; there’s about one per decade worldwide, according to a 2009 study. Symptoms often take weeks to appear and include abdominal pain on your upper right side, sudden nausea and vomiting, and fatigue, according to the Mayo Clinic. Here are signs your liver is in trouble.

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Yellow pool float, ring floating in a refreshing blue swimming pool
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Two more potential stomach bugs

Somehow, the CDC knows that the average person has about 0.14 grams of poop on their bottoms at any given time. This can wash off in the pool, and this is what exposes swimmers to a variety of diarrhea-causing illnesses. Two additional germs, Shigella and Norovirus, can cause outbreaks in pools. Shigella causes bloody diarrhea, stomach cramps, and fever, but you’ll most likely recover without needing treatment. Norovirus, which is extremely contagious and has been found in pools, lakes and rivers, fountains, and hot springs, produces sudden projectile vomiting and diarrhea (fun!) for 24 to 72 hours, so sufferers have to watch out for possible dehydration.

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Top view - young couple relax in swimming pool sitting at bubble bath
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Beware of hotel facilities

Hotel pools often get less attention. That may be why, as the CDC notes, most illness outbreaks are linked to hotel pools and hot tubs. Dr. Wiant’s tip for checking out the water: Peer into the deep end—you should be able to see the bottom or drain. Feel the sides of the pool—they shouldn’t be slimy. Finally, give the air a sniff. If you can’t see the drain, the sides are slimy, or the chlorine is pungent, take a pass on that pool or hot tub.

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Young asian woman relaxing in swimming pool at spa resort.relaxing concept.
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Always shower first

You may have seen signs at the pool advising that all swimmers shower before taking a dip, but 52 percent of adults never do before taking a plunge, according to the Water Quality & Health Council. “You’d be surprised how many bacteria are on the skin,” says Dr. Wiant. “To get those pathogens off your body effectively, you really need soap. At the very least, rinsing off for one minute has been shown to physically remove a good amount of contamination,” he says. This summer, be part of the solution not the problem. Let’s work together to get that percentage up to 100 and we’ll all be healthier for it. Don’t miss the 42 secrets lifeguards desperately want you to know.