Millions of Americans chose swimming as a way to get fit and have some fun, especially in the summer months. Public pools are accessible to most neighborhoods, and they offer open-swim sessions year round. Pools are also a common feature in many private health clubs, fitness centers and hotels.

With all these swimmers sharing the same pools, it’s vital to be aware of water-borne germs that can make you and your family sick. The Centers for Disease Control and Prevention even has a name for infectious ailments caused by germs in pools: recreational water illnesses (RWI). These illnesses include a wide variety of infections: gastrointestinal, respiratory, skin and wound, to name a few. The water-borne illness reported most commonly is diarrhea.

Used Properly, Chlorine Kills Germs—But Not Right Away

Just one swimmer with diarrhea can contaminate the water in a swimming pool, even if it’s Olympic sized. Other swimmers can ingest those germs by swallowing small amounts of water.

Isn’t chlorine supposed to kill these germs? Yes, chlorine does destroy most contaminants—but only if the chlorine is used at proper disinfection levels and if water conditions (pH and temperature) are ideal. But even when chlorine is properly used, some contaminants are chlorine tolerant. These germs will eventually succumb to chlorine, but it might take hours—or even days. In the meantime, those germs are swimming in the pool along with all the humans.

How to Protect Yourself, Your Family and Other Swimmers

You can avoid spreading and catching pool-borne germs by taking a few precautions.

• Don’t swallow pool water. Instruct children to try not to get pool water in their mouths at all.
• Before you get in the water, shower with soap. Wash your hands thoroughly after changing diapers or using the bathroom.
• Don’t go swimming when you have diarrhea. Don’t take children swimming when they have diarrhea.
• Check children’s diapers often.
• Don’t change children’s diapers at poolside. Germs can end up in the pool.