Those red eyes you get from swimming aren’t caused by chlorine, according to an official with the Centers for Disease Control and Prevention.

For their annual Healthy Swimming Program, the Centers for Disease Control (CDC) teamed with Water Quality and the Health Council and the National Swimming Pool Foundation to educate Americans about the dangers of pools and how to stay healthy when swimming, Women’s Health reports.

Beach went on to say that the cough you can get from an indoor pool is also caused by the chemical reaction. The chlorine isn’t what causes the irritation in your lungs; it’s pee.

There’s actually been an increase in disease outbreaks from public swimming pools, according to Beach, thanks in large part to those swimming while they have diarrhea. Those with diarrhea don’t even have to defecate in the pool to spread disease, but just have the germs on their body, which is why the CDC encourages swimmers to shower before getting in the pool.

“We have a new parasitic germ that has emerged that’s immune to chlorine,” says Beach. “We’ve got to keep it out of the pool in the first place. We need additional barriers.”

The misconception that chlorine just eliminates all germs upon contact is untrue, and it takes time to properly disinfect for each germ. While chlorine kills most bacteria such as E. Coli in less than a minute, it takes at least 16 minutes to kill Hepatitis A, and the Cryptosporidium parasite can last in the swimming pool for over 10 days.

The CDC says the only way to prevent recreational water illnesses is to keep germs out of the pool in the first place and to practice the following steps for healthy swimming: