Wells and cisterns

How often to test

Test your well water every season — spring, summer, fall, and winter. If seasonal testing isn't possible, take three samples one to three weeks apart. A single sample is not representative of your water quality. You can test as often as you like.

Test your well immediately after:

• Any repairs to the well
• Extended periods of non-use, such as at a seasonal residence
• Flooding
• Any change in surrounding land use
• Any change in the water's clarity, colour, odour or taste

Bacterial testing does not detect chemical contamination. If you're concerned about chemicals in your water, you can arrange testing through a private laboratory at your own expense.

How to take a water sample

1. Get a sample bottle
   Pick up a free testing kit from a test kit location near you. Only water collected in these bottles will be accepted.
   
   
2. Plan your timing
   Take your sample when you can drop it off within 24 hours. Samples can only be dropped off Monday to Thursday. Samples dropped on Friday will not reach the lab within the 48-hour limit.
   
   
3. Use an indoor tap
   Remove any aerator, screen or attachments from the faucet. Use an inside tap — not an outdoor faucet or garden hose.
   
   
4. Disinfect the faucet spout
   Swab the tap end with an alcohol swab or diluted bleach solution (one part bleach to 10 parts water). Do not use a flame.
   
   
5. Flush the tap
   Run cold water for three to four minutes to clear standing water from your plumbing.
   
   
6. Fill the bottle carefully
   Remove the lid without touching the inside or setting it down. Do not rinse the bottle. Fill to the marked line and close firmly.
   
   
7. Keep it cool
   Store the sample in a cool place (not frozen) until drop-off. Do not leave it in a warm space, such as a warm car trunk.
   
   
8. Drop off within 24 hours
   Deliver to a water test kit location. Samples older than 24 hours may not be processed.

Getting your results

• Results are mailed within five to 10 business days
• Call the automated results line at 1-877-723-3426 five business days after dropping off your sample. Have your bottle PIN ready.
• Visit the Online Water Testing Portal

If your water tests positive for Total Coliform or E. coli, stop using it for drinking, cooking or personal hygiene until your water is safe. Here's what you can do in the meantime

Bathing and showering
Adults may shower as long as no water is swallowed. Sponge baths are recommended for children. Wash hands in safe water after bathing.

Brushing teeth
Use bottled or boiled water.

Drinking water
Use bottled water or boil well water at a rolling boil for at least one minute. Refrigerate boiled water until use.

Food preparation
Use bottled or boiled water to wash fruits and vegetables and make juice. Food cooked for five or more minutes does not require pre-treated water.

Handwashing
Wash hands normally, then follow with an alcohol-based hand sanitizer.

Laundry and dishes
Laundry can continue as usual. Use bottled or boiled water for hand-washing dishes.

Discard any ice made with contaminated water.

After unsafe results, disinfect your well and get three consecutive satisfactory samples before returning to normal use.

If test results show unacceptable levels of Total Coliforms or E. coli, disinfect your well with household bleach and, if possible, identify and eliminate the source of contamination.

Bleach amounts

Drilled well

142 millilitres (5 ounces) per 7.5 metres (25 feet) of well depth

Dug well

1 litre (1 quart) per 1.5 metres (5 feet) of well depth

Use the Public Health Ontario disinfection calculator to confirm the amount needed for your well.

Disinfection steps

1. Mix the required bleach with several litres of water and pour down the well.
2. Run water through all indoor taps until you can smell bleach at each tap.
3. Do not use the water for 12 hours.
4. After 12 hours, run water through an outside hose (away from the septic system) until the bleach smell is gone.
5. Wait at least two days before taking a sample.
6. Get consecutive satisfactory samples — collected one to three weeks apart — before your water is considered safe. Assume it is unsafe until all three results are satisfactory.

It's recommended to have a permanent treatment system installed to ensure your water remains safe over time.

Always use a licensed well contractor. As a private well owner, you have legal obligations under the Ontario Well Regulation, including requirements for construction, maintenance, documentation and abandonment.

• Licensed well contractors list
• Water supply wells: technical bulletins
• Ontario Well Record Information Map

Email the Ontario Wells Help Desk or call 1-888-396-9355 (Ontario residents only).

Inspect your cistern annually for:

• Sediment, bio-film (slimy coating) or debris
• Cracks or seepages
• Ill-fitting lids or broken vent screens

Maintain the cistern so bugs, rodents and surface water runoff cannot enter. Do not direct rainwater into the cistern; bacteria from bird and animal droppings, dust, leaves and chemical residues from roofing materials can contaminate the water.

Refill only with potable water from an inspected water hauler.

How often to test

Test seasonally — spring, summer, fall and winter. If seasonal testing is not possible, take three samples one to three weeks apart. Test a minimum of four times per year.

The best time to sample cistern water is when contamination risk is highest. This is usually early spring, after an extended dry spell, following heavy rain, or after a long period of non-use.

Also test immediately after:

• Any repairs or replacements
• Extended periods of non-use, such as at a seasonal residence
• Flooding
• Any change in surrounding land use
• Any change in the water's clarity, colour, odour or taste

How to take a water sample

Pick up free test kits at a water test kit location. Keep samples cool and drop off within 12 hours of collection — samples must reach the testing lab within 48 hours.

Drop-off is Monday to Thursday only.

Getting your results

If you submitted your water sample information online or on paper, your results will be delivered by a text message or automated phone call within two to five days.

If you have questions about your water sample collection, the online portal or your results, contact Public Health Ontario's Laboratory Customer Service.

If your cistern water tests positive for bacteria, stop using it for drinking, cooking or personal hygiene.

The same precautions apply as for well water. Use bottled or boiled water for drinking, food preparation, brushing teeth and handwashing. Laundry can continue as usual.

Disinfect your cistern and resample before returning to normal use.

Empty and clean the inside of your cistern every one to two years. During cleaning:

• Remove sediment and debris
• Check and repair any cracks or seepages
• Remove any bio-film

Confined space warning

A cistern requiring physical entry for maintenance is a confined space. Hazardous gases or low oxygen levels may be present. Only individuals trained in confined space entry should enter a cistern.

After cleaning, disinfect the cistern before refilling.

Disinfect your cistern:

• After cleaning
• If it has become or may be contaminated
• If a lab result shows contamination
• If an inspection reveals a contamination concern

Disinfection steps

1. Arrange at least a seven-day supply of bottled water before starting (approximately 1.5 litres per person per day)
2. Add 4 ounces of household unscented bleach (5.25 per cent) per 1,000 gallons of water
3. Mix the bleach and water in the cistern with a large clean object
4. Run each water line in the house one at a time, including flushing all toilets and running all baths and showers, until you notice a chlorine odour. If no odour appears, add a little more bleach.
5. Let stand overnight. A minimum of 12 hours contact time is required.
6. Do not drink the water or use it for brushing teeth or washing fruits and vegetables until test results confirm it is safe. Bathing, showering, laundry and toilet flushing are safe during this period.
7. After at least three days, submit a water sample for bacterial testing

It's recommended to have a permanent treatment system installed to ensure your water remains safe over time.