Cryptosporidium is a microscopic parasite that causes the diarrheal disease Cryptosporidiosis, also known as “Crypto”. It is the leading cause of waterborne disease in the United States and can be spread through drinking water and recreational water. Other sources of infection include consuming uncooked food with Crypto and touching your mouth with Crypto-contaminated hands.

While there are many species of Cryptosporidium, only some are able to infect humans. The parasite lives in the intestine of an infected person or animal and is passed, and spread, through fecal matter. The parasite is protected by a hard outer shell, which allows it to survive for an extended period of time outside of a host and makes it tolerant of disinfection by chlorine.

A water source may become contaminated by Cryptosporidium if the feces of an infected person enters the water, which can occur by sewage overflows, improperly maintained sewage systems, and polluted storm and agricultural runoff. Wells are particularly vulnerable to Cryptosporidium after a flooding event, especially if the well is shallow, a dug or driven (bored) well, or submerged under water for a long time.

If you suspect your water is contaminated, contact a state certified laboratory about getting your water tested.

Cryptosporidium may be killed or inactivated by bringing the water to a rolling boil for one minute (longer in higher elevation). It should then be allowed to cool in a clean, sanitized container with an air-tight cover and refrigerated.

Some point-of-use filters will remove Cryptosporidium, but not all. According to the CDC, home water filters with the label “reverse osmosis”, “absolute pore size of 1 micron or smaller”, “tested and certified by NSF Standard 53 for cyst removal,” and “Tested and certified by NSF Standard 53 for cyst reduction” will remove or reduce the Cryptosporidium contamination.