Coliform bacteria in well water.

Asked January 15, 2020, 4:32 PM EST

I work at a small rural school where our well water is tested by the local health department. We have been testing positive for coliform bacteria occasionally over the last year. The man doing the testing is recommending we get rid of our classroom pet, a cat, who will occasionally drink water from the sink. Is it possible for an (indoor) cat drinking at a faucet to contaminate the well? Incidentally we tested positive months before the cat was born, but he persists that it's the most likely explanation.

Ionia County Michigan

1 Response


There is a possibility that the cat can contaminate the faucet, but that should not find its way back to the well. I recommend contacting the Health Department to try to get more of an explanation. (616) 527-5341 ext. 493

Other common explanations for bacteria in well water (1) is from a cracked wellhead where surface water can seep into the well; (2) from the flooding of the wellhead; (3) contamination from a failing septic system (even if a system is new, for example it can fail in cases where the water table has moved up).