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Well Water Safety

What Should I Do If My Well Water Is Contaminated?Kettle Boiling

Immediate Actions

  • STOP using the well water.
  • If you continue to use it, bring it to a rolling boil for at least one minute before using it for:
    • Drinking
    • Making infant formula, juices, ice or recipes
    • Washing food or dishesNo tap water
    • Brushing your teeth
    • Rinsing contact lenses
  • Consider using alternative water sources such as bottled water or municipal supply, if available

Future Actions

Scenario One: 1 - 5 Total coliform per 100 mL and 0 E. coli per 100 mL

  • Re-sample using Best Practices (See Taking a Water Sample)
  • If results of re-sample are 0 Total coliform per 100 mL and 0 E. coli per 100 ml, no further action is required.

Scenario Two: 1 - 5 Total coliform per 100 mL and 0 E. coli per 100 mL

  • Re-sample using Best Practices (See Taking a Water Sample)
  • If results of re-sample are 1 - 5 Total coliform per 100 mL and 0 E. coli per 100 mL, please follow remedial steps below.

Scenario Three: ≥ 6 Total coliform per 100 mL and 0 E. coli per 100 mL

  • Please follow remedial steps below.

Scenario Four: Water sample is positive for E. coli

  • Please follow remedial steps below.

Remedial Steps

  1. Conduct a visual inspection of your well in an attempt to identify the reason for the adverse water quality. The Homeowner Well Maintenance and Inspection Checklist (PDF) will act as a guide to help you with the inspection.
  2. Disinfect your well (see Dug & Bored Well Disinfection and Drilled Well Disinfection) and entire household plumbing system. Wait one (1) week to re-sample for bacteriological testing in order to ensure that all traces of chlorine have been flushed from the system.
  3. Consult a licensed well technician and a water treatment specialist to identify the issue and to eliminate it if your well water quality continues to be chronically adverse.

NOTE: Your well water supply is ONLY deemed safe to drink after you have received three (3) consecutive water results of 0 Total coliform per 100 mL and 0 E. coli per 100 mL, with each sample taken 1 to 3 weeks apart.

If you have any questions, concerns or require further assistance regarding your well, please contact the Health Department’s Environmental Helpline at 905-723-3818 or 1-888-777-9613. Together, you and our public health inspector may be able to:

  • Identify potential sources of well contamination
  • Discuss proper inspection and maintenance of your well
  • Discuss procedures for disinfecting your well water
  • Discuss water treatment devices if your well is chronically contaminated.