Fecal germs in pools are making people sick, CDC says — here's how to protect yourself

As summer peaks, the CDC is reminding swimmers that filtration and chlorine disinfection can only do so much to combat germs in swimming pools, but there are steps one can take to avoid getting sick.

There is a very good reason that pools and other swimming facilities post warnings that anyone who has or has had diarrhea in the prior two weeks should stay out of the water — it’s because one person with diarrhea has the potential to contaminate an entire properly chlorinated pool or water park.

Recreational water illnesses (RWIs) are spread when water that has been contaminated with chemicals or germs is swallowed. Fecal matter or urine (yes, people really are frequently peeing in pools) from people relieving themselves in the pool contribute significantly to the spread of RWIs.

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Most of the germs that cause RWIs won’t last longer than a few minutes in a chlorinated pool, but some, like Cryptosporidium, can live in chlorine treated water for about 10.6 days. Unlike other RWIs which tend to have much shorter symptomatic periods, Cryptosporidium can produce symptoms for up to three weeks.

Outbreaks of cryptosporidiosis have increased an average of 13 percent annually in recent years, and exposure to treated recreational water — in pools, water parks and water playgrounds — was associated with 153 outbreaks which resulted in 4,232 cases from 2009-2017.

E.coli will only survive in a properly chlorinated pool for about a minute, but the Hepatitis A virus will survive for about 16 minutes. The Giardia parasite will survive for about 45 minutes, and Cryptosporidium’s 10.6-day lifespan translates to about 15,300 minutes.

Norovirus, which causes vomiting and diarrhea that lasts for up to 72 hours, is another virus that can be found in pool water, though occurrence is more rare than other RWIs, and it is the leading cause of acute gastroenteritis (intestinal infection) among American children under the age of 5.

“Children are prime targets for norovirus and other germs that can live in lakes and swimming pools because they’re so much more likely to get the water in their mouths,” said Michael Beach, Ph.D, the CDC’s associate director for healthy water. “Keeping germs out of the water in the first place is key to keeping everyone healthy and helping to keep the places we swim open all summer.”

The CDC offers a few tips for swimmers to protect themselves and their families.

“Keep the pee, poop, sweat and dirt out of the water!” the CDC urges.

Every swimmer should shower before entering the pool, never urinate or defecate in the pool, never swallow the water and anyone with diarrhea should stay out of the water.

Hourly breaks from the water are also suggested so that children have ample opportunity to use the restroom and so that parents can check diapers on younger kids and change them in a bathroom or diaper-changing area — not by the pool where germs can easily spread.

Finally, you can check the free chlorine level and pH before you get in the pool to make sure an error hasn’t occurred. Pool testing strips can be purchased at most hardware stores, superstores and pool supply stores.

The proper free chlorine level of pools is 1-3 mg/L or parts per million (ppm), and the pH should be between 7.2-7.8 to maximize the chlorine’s ability to wipe out germs.

In hot tubs, the free chlorine level should be at 2-4 ppm, or if using bromine to disinfect instead, the free bromine level should be at 4-6 ppm. pH should also be between 7.2-7.8.