How to Treat Swimming Pools for Cryptosporidium

Cryptosporidium in a swimming pool can cause diarrhea.

Cryptosporidium, a parasite that infects people and animals, is transmitted to others through contact with infected stool. Swimming pools are ripe breeding grounds for cryptosporidiosis, a diarrheal illness that develops as a result of a Cryptosporidium infection. The parasite can easily contaminate your pool, so eradicate it by focusing on your pool's filtration system and levels of chemicals and dissolved solids.

Things You'll Need

• Chlorine
• Diatomaceous earth filter

Instructions

1. Close your pool and keep it closed until you have completed treatment for Cryptosporidium. Anyone who has had diarrhea recently should not be allowed to swim in your pool until they have been free of symptoms for two weeks. The parasite can continue to be expelled through feces even while a person is treated for cryptosporidosis.

2. Install a diatomaceous earth filter in your pool, if possible. According to the Johnson County, Kansas Environmental Department, the parasite can slip right through many cartridge and sand filters, but may be more easily trapped in an earth filter.

3. Bombard your pool with high levels of chlorine and other non-halogen disinfectants. While the Centers for Disease Control explains that Cryptosporidium is resistant to halogen and normal levels of chlorine, increasing the chlorine concentration time value to 9,600 can kill off the source of infection.

4. Keep your pool filter running --no matter what type you have--continuously to get rid of the parasite. Depending on the level of contamination and efficiency of your filter, you may need to run your filtration system for several days. Public pools may be more severely affected than a private, backyard pool.

5. Test the water for chemical levels and dissolved solids frequently. The pH levels should range from 7.2 to 7.8, calcium hardness between 200 and 400 parts per million (ppm) and dissolved solids should read lower than 2,500 mg per liter. Proper levels will ensure your pool is safe, reducing the likelihood of recurring contamination.

References

• CDC: Fact Sheet: Cryptosporidium Infection
• Johnson County Environmental Department: Pool Inspection: Cryptosporidium and Cryptosporidiosis
• CDC Morbidity and Mortality Weekly Report: Cryptosporidium Infections Associated with Swimming Pools--Dane County, Wisconsin, 1993