Health experts are warning about a chlorine-resistant parasite that could pose problems in pools this summer.
Cryptosporidium could cause symptoms including stomach cramps and diarrhea.
The parasite, also known as crypto, can survive in water for up to 10 days.
Swimmers are advised to shower before jumping in the pool to prevent introducing bacteria to the water.
The Centers for Disease Control and Prevention says it is seeing infections from backyard pools in addition to public pools and water parks. The CDC says it is working on guidelines for all public pools to start using.
In recent years, nearly 1,800 people have gotten sicken from crypto and one person has died because of it.