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Free well water testing

How to sample your well water for bacteria

Why should you test your well water?

Drinking contaminated water can make you sick and can even be fatal. Bacterial contamination causes stomach cramps and/or diarrhea as well as other problems. Chemical contamination is equally dangerous.

Make sure your water supply is safe to drink by testing it regularly - test for bacteria three times a year and after major plumbing work. We also recommend testing for nitrates. If you are in an agricultural area, you may also wish to test for pesticides, herbicides, gasoline and solvents.

You should be aware that the bacterial stability of water cannot always be determined from a single sample. To establish drinking water quality, initially submit three samples at least one week apart. If the well shows acceptable coliform/E.coli counts, then sample three times a year. Do not send several samples at the same time.

How to sample your well water for bacteria

Bacterial testing for private wells is performed free of charge by the Ontario Ministry of Health Public Health Laboratory at 2380 St. Laurent Blvd. Sample bottles are available for pickup at that laboratory, and at water testing pickup and drop-off locations.

  1. Obtain a water sample bottle
  2. Do not touch the bottle lip and do not rinse out the bottle
  3. Remove aerators and other attachments from your tap
  4. Let the cold water run for three minutes before sampling
  5. Fill the bottle to "fill line" directly from the tap without changing the flow of water. Replace cap tightly.
  6. Samples must be refrigerated after collection. During transportation, put bottle in a cooler if possible
  7. Write down the bar code on the pink card and retain it for future reference
  9. Keep the pink card - you will need the number to obtain your results
  10. Return the sample and form within 24 hours of collection


You will need your pink card with the bar code number. Test results are available by :

Mail : you will receive the results by mail in seven business days.
In-person : visit the Public Health Lab with identification, 2380 St.Laurent Blvd., three business days after dropping off your sample.
Call 1-877-723-3426, two or three business days after dropping off your sample. Follow the telephone instructions.

Rural well water bottle pick up and sample drop off locations

Ottawa Public Health (OPH) is improving the well water testing program to make it more convenient for Ottawa residents living on residential well systems to have their well water tested for free.

OPH has established permanent sites across Ottawa where well owners can drop off their water samples and pick up new bottles for future testing. As part of the improved program, residents can drop off their water samples every Tuesday at one of these locations (see chart below). 

Residents wishing to drop off their samples and pick up testing bottles may also continue to do so during regular business hours at OPH’s main office – Mary Pitt Centre (100 Constellation Drive) or at the Ontario Public Health Laboratory (2380 St. Laurent Blvd).

Location Address Hours
Mary Pitt Centre

100 Constellation Dr.

Main floor lobby

Monday to Thursday:  8:30 am to 4:30 pm

Friday: 8:30 to 11 am

Public Health Ontario Laboratory 2380 St. Laurent Blvd

Monday to Friday:  8 am to 4:30 pm

This service will be provided year round and testing for bacteria continues to be offered free of charge. OPH also recommends testing for nitrates. If you are in an agricultural area, you may also wish to test for pesticides, herbicides, gasoline and solvents.

For any further questions or information, please visit WaterTesting or call OPH at 613-580-6744.


Residents can drop off their water samples every Tuesday at one of these locations. Pick up of new bottles for future testing can be done during each location’s hours of operation.




JT Bradley Store – Navan

1220 Colonial Road

6 am to 9 pm

Midori Market – Sarsfield

2950 Colonial Road

6:30 am to 8:30 pm

Orleans Client Service Centre

255 Centrum Boulevard

8:30 am to 4:30 pm

Peladeau Grocerie – Vars

5877 Buckland Road

8 am to 9 pm


Residents can drop off their water samples every Tuesday at one of these locations. Pick up of new bottles for future testing can be done during each location’s hours of operation.




Mackinnon Foodland –Greely

1347 Meadow Drive

24 hrs

Manotick Library

5499 South River

10 am to  8:30 pm

Metcalfe Client Service Centre

8243 Victoria Street

8:30 am to 4:30 pm

North Gower Library

6579 Fourth Line Road

10 am to  8:30 pm

Osgoode Foodland

5669 Osgoode Main Street

8 am to  9 pm

Rural Ottawa Support Services Manotick

1128 Mill Street

8:30 am to 4 pm

Osgoode Township Historical Society 7814 Lawrence Street 9 am to 5 pm


Residents can drop off their water samples every Tuesday at one of these locations. Pick up of new bottles for future testing can be done during each location’s hours of operation.




Carp Library

3911 Carp Road

10 am to 8:30 pm

Darvesh Grocery – Kinburn

3084 Kinburn Side Road

7 am to 8 pm

Dunrobin Meat and Grocery

2808 Dunrobin Road

7 am to 8 pm

Kinburn Client Service Centre

5670 Carp Road

8:30 am to 4:30 pm

King's Your Independent Grocer - Richmond

5911 Perth Street

 8 am to 10 pm

Lighthouse Restaurant – Constance Bay

655 Bayview Drive

7 am to 9:30 pm

What the test results mean

Water quality test results

You will receive the results by mail in approximately seven days. Results are also available at the laboratory four days after submission.

If you need help interpreting the results, please contact the City's Environmental Health Program at 580-6744 ext. 23806, or the provincial laboratory at 736-6800.


Nitrates are the end result of a chemical reaction; they are not bacteria. The presence of nitrates in your well water is usually the result of residential yard or agricultural fertilizers or seepage from septic tanks.

Infants less than six months old can become sick from drinking formula made with water high in nitrates. The nitrates in the formula reduce the amount of oxygen carried by the blood and could cause "blue baby syndrome" (Methaemoglobinemia). If you have an infant less than six months, it is recommended to use bottled water.


Well water should be analyzed for the presence of sodium. Individuals who are on a sodium (salt) reduced diet should consult with their physician if the level of sodium in their well water exceeds 20 mg/L.

Most domestic water softeners increase the level of sodium in the drinking water. In order to reduce sodium consumption, a separate unsoftened water supply (by-passing the water softener) should be provided for drinking and cooking purposes.

Bacteriology interpretation

Drinking water is tested for the presence of two groups of bacteria: total coliform bacteria and E.Coli. Total coliforms exist in animal waste, soil and vegetation. The presence of these bacteria in you well may suggest that surface water is seeping into your well

E.Coli bacteria are in human and animal digestive systems. Their presence in your well suggests your water may be contaminated by manure or sewage from a local septic system or feedlot. E.Coli can be dangerous to your health.

This scale does not apply to testing of surface water used for swimming.



What It Means

1 to above 80

1 to above 80

Unsafe for drinking. This water is contaminated and should not be used for drinking under any circumstances.

6 to 80


Unsafe for drinking. Contamination is not likely to be of sewage origin unless it is far removed from the water source or unless there has been a delay in receipt of the sample. Common in new wells before disinfection and shallow dug wells that are not properly sealed.



Safety is doubtful on the basis of a single test. Safe for drinking only if testing of three samples collected one to three weeks apart shows no higher and the condition is judged stable, and the well is protected and located at least 30 m (100 ft.) away from any source of human or animal waste.



SAFE for drinking. Maintain regular testing.



Safety is doubtful. Not recommended for drinking. No coliform bacteria could be detected because the sample was overgrown with other bacteria. This condition frequently occurs with new wells, dug wells receiving soil drainage, or wells that have been idle for some time. Disinfect the well and collect another sample, clearly identified as "repeat sample".

What to do if your well water is contaminated

How to sterilize your drinking water

If your drinking water results show that your well water is contaminated and unsafe to drink, follow these guidelines until your water supply is safe again.

Use only one of the following options for a safe supply of drinking water:

  • Bring water to a rolling boil and then boil it for at least one full minute. A full rolling boil is a vigorous boil that can not be stopped by stirring the water). OR
  • Treat water by mixing two drops (0.1 ml) of unscented household liquid chlorine bleach (about 5.25 per cent chlorine) with one litre of water. Cover and let stand for 30 minutes before you use it. You should notice a slight chlorine smell after the 30 minutes.
  • Use commercially bottled water.

Refrigerate boiled or treated water in clean containers.

What water to use for washing and to use for pets

Handwashing: Use bottled, boiled or treated water (as above) or use the usual supply for handwashing, then follow with an alcohol-based hand sanitizer.

Food Preparation: Use bottled, boiled or treated water to make juice or formula or to wash ready-to-eat foods such as fruits and vegetables. If the food will be boiled for longer than five minutes during the cooking process, it is not necessary to use treated water. Do not use ice cubes made with the unsafe water.

Bathing/showering: Adults may continue to use the usual supply, as long as no water is swallowed. After you bathe or shower, use treated water to wash your hands. Give sponge baths to children, using treated water.

Brushing teeth: Use boiled, bottled or treated water.

Laundry: Use your usual source of water.

Dishwashing: Use bottled, boiled or treated water.

Pets: Use bottled, boiled or treated water.

Livestock: Consult a veterinarian regarding water for livestock.

Garden: It is recommended that a vegetable garden or a fruit orchard be watered using treated or boiled water.

How to disinfect a well

You can easily disinfect your well contaminated with bacteria by "shock-treating" it with ordinary chlorinated household bleach containing 5.25 per cent sodium hypochlorite. Don't use scented bleach for this purpose. Buy fresh bleach to do this because the chlorine in bleach is unstable and evaporates over time. (Bleach loses half its strength in six months.)

Dug Wells (three feet (1 m) in diameter): Add one quart (one litre) of household bleach for every five feet (1.5 m) of water depth.

Drilled Wells (six inches (15 cm) in diameter): Add five ounces (142 mL) of household bleach for every 25 ft (7.5 m) of water depth.

Well (Sand) Points (two inches (5 cm) in diameter): Add about one quarter ounce (6 ml) of household bleach for every 10 ft (3 m) of water depth.

Do not drink the water until you receive satisfactory water quality test results.

1. Refer to your well record to find out how deep your well is. If you don't know how deep the water is in the well, use the well depth to estimate how much bleach to add.

2. Remove or bypass any carbon filters in the system. (These filters will remove chlorine from the water, thus preventing the pipes beyond the filter from being disinfected.)

3. Pour the required amount of household bleach into the well air vent or by removing the well cover.

4. If possible, agitate or mix the well water by using a clean hose to pump the chlorinated water back into the well, flushing down the well casing and water lines above the water level.

5. Disconnect the pump filter, run water through all taps for 20 minutes until a strong chlorine smell is detected. (If there is no chlorine smell, repeat the chlorine treatment.)

6. Drain the water heater and fill with chlorinated water. Backflush the water softener and all filters except carbon filters. Then wait 12 hours.

7. Run the rest of the treated water through an outside hose away from the septic tank system (excess chlorine will kill the bacteria necessary for breaking down wastes) and away from surface water courses i.e. rivers and ditches.

8. Stop running the hose when the smell of chlorine is gone. Run clear water through the faucets.

9. Do not drink the water until test results prove it is safe to drink.

10. Retest 48 hours after chlorination is complete. Two bacteria-clear tests over one to three weeks is a strong indicator that the water is safe to drink.

11. If any test shows contamination, repeat the disinfection process from the beginning.

If shock chlorination doesn't correct the problem, you will need professional help to determine whether a new well (such as a drilled well instead of a dug well) is required, or whether an on-site water disinfection system will deliver the desired results.

Bleach required to disinfect a well

1) Drilled wells

Well Depth

Bleach Volume



fluid oz.


































2) Dug wells

Well Depth

Bleach Volume






















3) Introducing chlorine to a sand point well (well point)

Before starting the disinfection process, the outside of the sand point well (well point) and all associated equipment should be cleaned and disinfected. Homeowners can use disinfectant wipes or alcohol swabs. Unscented household bleach can be introduced in the well by removing the well cap. Ensure your pump does not run dry.

Using a drain plug opening, pressure gage opening outlet pipe, or other opening into the pressure tank, add chlorine bleach or other chlorine into the pressure tank, so that the water in the tank contains approximately 50 ppm free chlorine. This will take approximately 3 (three) tablespoons, or 1 ½ ounces of bleach for each 10 (ten) gallon of tank capacity (a 50-gallon tank, for example, will require approximately ¾ (three fourths) of a cup of bleach.

Visit the City-owned Wells if you would like to know how we purify communal wells.