Well Water and Coliform Bacteria: What Every Homeowner Should Test For

If your home draws water from a private well, no municipal authority is testing it for you. Coliform bacteria — including the dangerous E. coli strain — can enter your well through surface runoff, aging well casings, or nearby septic systems, often without any visible change in your water's colour, taste, or smell.

What Is Coliform Bacteria?

Coliform bacteria are a group of microorganisms used as indicators of water quality. Their presence signals that your water source may have been contaminated with fecal matter — from livestock, wildlife, or failing septic infrastructure. Total coliform counts above zero in a drinking water sample are considered a failure by Health Canada and the US EPA.

E. coli is the most serious coliform threat. Even low concentrations can cause severe gastrointestinal illness, and it poses particular risk to children, the elderly, and immunocompromised individuals.

When Should You Test Your Well?

Test your well water if any of the following apply:

• You haven't tested in the past 12 months
• You've experienced heavy rainfall or flooding near your property
• You've noticed changes in water odour, taste, or colour
• A neighbour's well has tested positive for bacteria
• You've recently had well repairs or pump replacement
• You're purchasing a home with a private well

How to Test for Coliform at Home

Professional lab testing is the gold standard, but it requires shipping a sample and waiting days for results. The AquaVial Well Water Testing Kit 2 Pack gives you lab-grade bacterial detection at home — no shipping, no waiting. Results arrive in 24–48 hours, and the two-pack lets you test now and retest after any remediation.

What to do if you test positive: Stop drinking the water immediately. Shock-chlorinate your well according to your provincial or state guidelines, then retest before resuming use.

The Bottom Line

Private well owners carry full responsibility for their water safety. Annual testing for coliform bacteria is the single most important thing you can do to protect your household — and it takes less than five minutes to start with the right kit.