Well and Cistern Maintenance for Residential Settings

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Well water

For those who obtain water from wells, it is important to make sure the water is clean and safe to drink.

Water may contain many microorganisms like E. Coli and Campylobacter that can make people sick, give you stomach cramps or diarrhea and in some cases can be life threatening.

Frequent sampling and testing of your drinking water will allow you to determine the quality of your water supply.

  • Testing and inspection
    • Wells should be tested seasonally (spring, summer, fall and winter). Instructions on how to take a water sample
    • Free testing bottles can be picked up at all Public Health locations and most Town Halls
    • If regular seasonal samples cannot be taken, then 3 samples, 1 to 3 weeks apart should be obtained. A single sample is not representative of the quality of your well water. You can test as often as you want
    • In addition to regular tests, well water should be tested immediately after:
      • Any repairs
      • The well has not been used for long periods of time (such as seasonal residences)
      • After flooding
      • There has been a change in the surrounding land use
      • There is any change in its clarity, colour, odour or taste

    Note: Bacterial testing does not provide information on the chemical water quality of your well water supply. If you are concerned about chemical contamination, you can have your water tested for chemicals by a private laboratory at your own expense.

  • Getting a bad result
    • Don't use water that has tested positive for Total Coliform or E.Coli. Don't use it for drinking, making infant formula and juices, cooking, making ice, washing fruits or vegetables, brushing teeth, bathing or showering.
    • If you want to continue to use your well water, bring it to a rolling boil for at least one minute. Your boiled water supply should always be refrigerated until it is used.
    • Consider using alternative water sources, such as bottled water or municipal supply if available.
    • Handwashing - use bottled, boiled or treated water (as above), or wash your hands normally and then use an alcohol based hand sanitizer available at your local pharmacy.
    • Food Preparation - use bottled, boiled or treated water to wash ready-to-eat foods such as fruits and vegetables and make juice. Water used in the preparation of food that requires cooking of five minutes or longer does not have to be boiled or treated previously. Discard ice cubes made with contaminated water.
    • Bathing/Showering - Adults may continue to shower as long as no water is swallowed. Sponge baths are recommended for children instead of tub baths. Use a safe supply of water if possible. After you bathe or shower, wash your hands in safe water.
    • Brushing Teeth - Use bottled, boiled or treated water.
    • Laundry - Continue to launder clothes as usual.
    • Dishwashing - Use bottled, boiled or treated water.

  • Disinfection

    If test results show an unacceptable level of Total Coliforms or E. coli, it is necessary to treat the well and, if possible, find and eliminate the source of contamination. Disinfection can be done using household bleach. Mix the bleach with several litres of water before pouring it down your well.

    • Drilled Well - 142 mL (5 oz.) of bleach for every 7.5 m (25 feet) of well depth
    • Dug Well - 1 litre (1 quart) bleach for every 1.5 m (5 feet) of well depth
    • Calculate your well disinfection rate
      1. Run water through all taps until you can smell the bleach. Do not use the water for 12 hours.
      2. After 12 hours, run the rest of the treated water through an outside hose away from the septic tank system. Stop running the water when the smell of bleach is gone.
      3. Wait at least 2 days before collecting a sample for testing.
      4. After completing this procedure, obtain three consecutive satisfactory samples to ensure your drinking water is safe. These should be collected one to three weeks apart. Assume your water is unsafe until you get these three satisfactory results.

  • Well construction

    It's important for homeowners to always use a licensed well contractor and understand their legal obligations as a private well owner. This includes requirements for well construction, maintenance, notification, documentation, abandonment, and licensing under the Well Regulation.

    Well construction, licensing and maintenance resources:

    The Ontario Wells Help Desk is also available at wellshelpdesk@ontario.ca or toll-free at 1-888-396-9355 (Ontario residents only).

Cistern water

Some rural residents obtain their drinking water from a reservoir or cistern typically made from concrete. A cistern is used most often in areas where wells do not provide sufficient water or have historically produced water that is unsuitable for drinking.

A properly constructed cistern filled with municipally treated water delivered by an approved water hauler should provide water that is safe to drink. A cistern still requires periodic inspection, cleaning, and disinfection. Poorly maintained cisterns are easily contaminated.

  • Testing and inspection
    • Use a cistern made from a material suitable for holding drinking water
    • Maintain the cistern in a manner that will prevent the entrance of bugs, rodents, and surface water runoff
    • Inspect the cistern annually for sediment, bio-film (slimy coating), debris, cracks and seepages, ill-fitting lids, and broken vent screens
    • Do not direct rainwater into the cistern. Bacteria from bird and animal droppings, dust, leaves, and chemical residues from roofing materials will contaminate the cistern
    • Refill the cistern with potable drinking water only. Potable water haulers typically obtain their water from a municipal water supply, and are inspected by Niagara Region Public Health. Get water hauler inspection reports.

  • Cleaning
    • Empty and clean the inside of the cistern every one to two years. You can remove sediment and debris, check and repair any cracks or seepages, remove any bio-film, and repair any damage. A cistern that requires entry into it for maintenance and cleaning should be considered a confined space. Hazardous gases or low oxygen levels may be present. Only individuals trained in confined space entry should enter a cistern
    • Disinfect the cistern after cleaning

  • Disinfection
    1. Disinfect the cistern:
      • After cleaning
      • If the cistern has become or may be contaminated
      • If a lab result indicates the cistern is contaminated
      • If an inspection reveals there is concern of contamination
    2. Add four ounces of household (5.25%) unscented bleach per 1,000 gallons of water
    3. Mix the bleach and water with a large clean object
    4. Run each water line (one at a time) in the house until a chlorine odour is noticed- that includes flushing all toilets, and running all baths and showers. If no odour is noticed, add a little more bleach to the cistern
    5. Let stand overnight (minimum 12 hour contact time required)
    6. After at least 3 days, submit a water sample for bacteria testing
    7. Do not drink the water (or use it for brushing teeth or washing fruits/vegetables) until you have received your test results. The water should be safe for bathing, showering, laundry, and toilet flushing
    8. It is recommended that at least a seven day supply of drinking water (bottled water) be arranged before starting this process (typically 1.5 litres per person per day should be enough)

  • Bacterial testing
    • Free sample kits for bacteria testing are available from Municipal Service Centers and Public Health
    • Sample freshness and temperature control is essential for proper testing for bacteria. We recommend you take the sample on your way to the drop off site. If that is not possible then bring the sample to the drop-off location within 12 hours of collection and keep it cool in transit and in storage
    • Samples must reach the testing laboratory within 48 hours of collection time
    • If sample test results indicate the drinking water supply is unsafe, stop drinking it. It is recommended to inspect the cistern and resample and test the water. If the re-sample results indicate the water is unsafe for drinking and the cistern appears clean and maintained, disinfect the cistern according to the procedure above. Make sure you are testing your water properly
    • Chronic unsafe test results indicate a likely need to install a permanent disinfection device such as a chlorinator or ultraviolet system. A professional should be consulted for assistance
    • Cisterns should be tested seasonally (spring, summer, fall and winter). If regular seasonal samples cannot be taken, then three samples, one to three weeks apart should be obtained. A single sample may not be representative of the quality of your cistern water. Continue to sample a minimum of four times per year. You can test more often if you want. The best time to sample cistern water is when the probability of contamination is greatest. This is likely to be in the early spring, after an extended dry spell, following heavy rains or after lengthy periods of non-use. In addition to regular tests, cistern water should be tested immediately after
      • Any repairs/replacement
      • The cistern has not been used for long periods of time (such as seasonal residences)
      • After flooding
      • There has been a change in the surrounding land use
      • There is any change in the water clarity, colour, odour or taste
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