Escherichia coli (a.k.a. E. Coli) includes a diverse and widespread group of bacteria, most of which are harmless to humans. However, E. coli strain 0157:H7 produces a toxin that can cause severe illness in infected individuals. This strain can be present in the guts of healthy cattle.
E. coli strain 0157:H7 can infect humans via their drinking water if the water source becomes contaminated with the feces of an infected cow or human. Contamination can occur through sewage overflows, improperly maintained sewage systems, and polluted storm and agricultural runoff. Wells are particularly vulnerable to E. coli 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.
E. coli 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.
Currently, there is no Point-of-Use (POU) or Point-of-Entry (POE) filter certified to remove E. coli from contaminated water. However, if you would like to disinfect your well, contact your local health department.