Recreational Water Illnesses (RWIs) are caused by germs or chemicals found in the water we swim in—whether it’s a pool, hot tub, water park, lake, river, or ocean. These illnesses can be contracted by swallowing, breathing in mist or aerosols, or coming into contact with contaminated water.

Contrary to popular belief, chlorine does not kill all germs immediately. Some, like Cryptosporidium (Crypto), are highly chlorine-tolerant and can survive in properly treated pools for days. Even swallowing a small amount of contaminated water can make you sick.

RWIs can cause a range of infections, including gastrointestinal, skin, ear, eye, respiratory, and wound infections. The most commonly reported RWI is diarrhea, often caused by pathogens such as Crypto, Giardia, Shigella, norovirus, and E. coli O157:H7.

With RWI outbreaks on the rise, it’s important for swimmers to stay informed and take precautions to protect themselves and others. Simple steps like not swimming when sick, avoiding swallowing pool water, and showering before swimming can make a big difference.

Maintaining proper pool chemistry is also critical. While most germs are killed quickly by chlorine, poor water quality increases risk. A 2010 study found that 1 in 8 public pools were closed immediately after inspection due to serious violations, including unsafe chlorine levels.

Learn more and stay safe—your health depends on it.