RWIs are illnesses that are spread by swallowing, breathing, or having contact with contaminated water from swimming pools, spas, lakes, rivers, or oceans. Recreational water illnesses can cause a wide variety of symptoms, including gastrointestinal, skin, ear, respiratory, eye, neurologic and wound infections. The most commonly reported RWI is diarrhea. Diarrheal illnesses can be caused by germs such as Cryptosporidium,  Giardia, Shigella, Norovirus, and E.coli.