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What makes your eyes red in the pool? It's not the chlorine

by Gina Vivinetto /  / Updated  / Source: TODAY

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If after a day of swimming in the community pool you notice bloodshot eyes, it's not the chlorine causing them to redden and sting.

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It's urine mixing with the chemicals.

“When we go swimming and we complain that our eyes are red, it’s because swimmers have peed in the water,” Michele Hlavsa, chief of the Center for Disease Control and Prevention’s healthy swimming program told TODAY. “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. It’s chlorine mixed with poop and sweat and a lot of other things we bring into the water with us.”

RELATED: What to know about dry drowning and how to prevent it

In fact, Hlavsa said, the stronger the chlorine smell at a pool, the more filled with pee it is. Healthy pools don’t smell like chemicals.

 Urine, not chlorine, causes eyes to burn and turn red while swimming. Shutterstock

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.

“I just don’t think this is on people’s radars,” she said. “People think waterborne disease is something that happens outside the United States. But really, we have plenty of them here.”

The recent CDC healthy swimming report found that one in five public wading or kiddie pools are closed because of violations, including improper PH levels, safety and disinfectant concentration. The CDC collected inspection data from five states in 2013 — the most recent year available — with the most public pools and hot tubs: Arizona, California, Florida, New York and Texas). Most inspections resulted in at least one violation.

WATCH: How to keep your children safe during swim season

Proper PH and disinfectant levels are important to stop the spread of germs in public pools.

RELATED: 30 easy steps to take your kids swimming

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, a germ that causes diarrhea, can live in chemical-treated water for ten days, says 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. 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?

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

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