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/ Source: TODAY
By Gina Vivinetto and Marguerite Ward

When you jump in the pool, you might be swimming in a lot more than you bargained for. Pools at hotels, rec centers and other public spots may be spreading nasty germs.

The biggest culprit of pool-related illness outbreaks is a hard-to-kill, diarrhea-causing parasite called Cryptosporidium, or crypto, that can resist the chlorine in swimming pools, according to a 2019 report from the Centers for Disease Control and Prevention. During 2009-2017, 444 cryptoporidiosis outbreaks resulted in over 7,000 cases, occurring in 40 states. Most of the illness outbreaks were linked to pools or water playgrounds, the CDC explained.

Cryptosporidium can lead to watery diarrhea that can last up to three weeks.

It's not just crypto hiding in pools. Have you ever had red, bloodshot eyes after swimming in a pool? It's not the chlorine causing them to redden and sting. It's urine mixing with the pool's chemicals.

When we go swimming and our eyes turn red, it’s because swimmers have peed in the water.

“The nitrogen in the urine combines with the chlorine and it forms what’s known as chloramine and it’s actually chloramine that causes the red eyes," Michele Hlavsa, chief of the CDC’s healthy swimming program told TODAY in 2015. "It’s chlorine mixed with poop and sweat and a lot of other things we bring into the water with us.”

How can you tell if a pool is clean?

There's at least one way to check if the pool you're about to swim in is clean or not. The stronger the chlorine smell at a pool, the more filled with pee it is. Healthy pools don’t smell like chemicals, Hlavsa said.

"It's not chlorine’s job to clean pee from a swimming pool. Its plate is full with E. coli and other germs. Once people start adding pee, poop, sweat and dirt to the equation, it starts to try to tackle those instead, leaving it with little energy for anything else," said Hlavsa.

Proper pH and disinfectant levels are important to stop the spread of germs in public pools. If you own your own pool, the CDC urges that you test the water.

Buy a pool tester at big box stores, pool supply stores and hardware stores. Check both the chlorine level and the pH.

  • Chlorine levels should be between 1 to 3 ppm.
  • The pH should be between 7.2 to 7.8. The pH is important because it determines how effective that chlorine is.

And, as far as chlorine is concerned, how’s this for a not-so-fun fact? Cryptosporidium can live in chemical-treated water for ten days, said Hlavsa.

The more of us who follow these tips from CDC, the more we'll all enjoy a day at the pool:

1. Shower before getting into the water.

Take a solid minute to wash dirt and germs off. Most adults admit they never rinse off before swimming, according to a 2018 survey of 3,000 adults by theWater Quality and Health Council, an independent chlorine producers industry group. A 2019 survey by the same organization found that 51% of respondents admitted to using the pool as a bathtub in place of the pre-swim shower, or instead of showering after exercise or yard work.

Also, rinse off your body again when you leave the water.

2. Got diarrhea or other bowel issues? Stay out of the water.

Is this asking so much?

In the industry survey from 2018, 17% of adults said they would swim in a pool within one hour of having diarrhea. And that's not including kids or babies.

3. Don’t pee or poop in the water!

We’ve heard this this since we were kids. If you have kids, nag them too. Also, keep in mind, a toddler’s swim diapers aren’t leak proof.

4. Don’t swallow the water.

Don’t even put it in your mouth. Are you even tempted to anymore?

As yucky as this info is is, pools and water parks can still be a fun part of everyone’s summer — if they follow the CDC’s suggestions.

The CDC report advises you to check your local pool to see if its latest inspection results are online or onsite.

TODAY health and wellness editor Gabrielle Frank contributed to this report. This updated story was first published in 2015.