The Regional Municipality Of York


Private Well Water Testing

Private Well Water Testing

Until further notice, private well water sample pick-up and drop-off is limited to two locations from Monday to Thursday only (closed statutory holidays). Please note that our locations will be closed from December 24, 2020 up to and including January 3, 2021 and will resume on January 4, 2021.

Georgina (pick-up and drop-off 8:30 a.m. to 9:30 a.m. and 10:15 a.m. to 11 a.m.)
24262 Woodbine Avenue
Keswick L4P 3E9

Newmarket (pick-up and drop-off 8:30 a.m. to 10 a.m.)
17150 Yonge Street (NW corner of Yonge and Eagle St)
Newmarket L3Y 8V3

Sample pick-up and drop-offs can be made at this location between 8:30 a.m. and 10 a.m. Monday to Thursday. Visitor and accessible parking is available near the main entrance, for your convenience. Please enter the vestibule of the building at the main entrance and follow safety protocols of wearing a mask and sanitizing your hands. Place the sample into the cooler provided. Sample bottles for pick-up will also be available.

Alternatively, water samples for private citizen drinking water samples can be dropped off at the Public Health Laboratory located at 81 Resources Road, Etobicoke, ON from Monday to Friday from 8 a.m. to 2 p.m. (closed statutory holidays).

For more information or questions about private well water quality, please contact Health Connection at 1-800-361-5653.

York Region provides water sample bottles, forms and information to local residents who own private wells and want to ensure their water is safe to drink. Sample bottles are available for pick up and drop off at several locations. Samples are sent to Public Health Ontario Laboratories to be tested for bacteria. Results of the water test can be received by telephone, mail or can be picked up directly from the Public Health Ontario Laboratories.

Well water should be tested regularly for bacteria. It is the owner’s responsibility to maintain and monitor their well. See the frequently asked questions for more details.

For more information on private well water testing, please contact Health Connection:
TTY: 1-866-512-6228 (for the deaf or hard of hearing) 


This service is for drinking water sampling only. You must own a private well to be eligible.

Municipal water is tested regularly by York Region and the local municipality. Water samples from a municipal supply are not analyzed by the Public Health Ontario Laboratory. See Drinking Water Quality and Monitoring for more information.


This service is available at no charge.

Frequently Asked Questions

When should I test my well water?

You should test your water:

  • When construction is complete and the well has been disinfected
  • When the well has not been used for a long time
  • At least three times a year (spring, summer and fall)
  • After snow melts
  • After a heavy rainfall or flood
When should I test my well water The Regional Municipality of York en-US

How do I properly take a water sample?

It is important to use the sampling bottles given by the lab, which are sterile 250 ml bottles with a white powder inside called sodium thiosulphate. The powder will stop the sampled water from degrading.

Samples must be collected and stored properly, and reach the lab within 48 hours. It is best to collect and drop off the sample on the same day, as this allows for enough time for transport of the sample to the lab. The public health laboratory may not test the water if it is received 48 hours from the time and date indicated on the form.

Taking a Water Sample

Select an indoor tap where you get your drinking water from such as the kitchen tap. Do not take a sample from a bathroom or laundry tap. Once you have chosen a tap, follow these steps:

  1. Get a water sample bottle from one of the York Region Health Services offices listed above. You can keep a bottle for one year provided it has not been opened
  2. Do not open the sample bottle until you are ready to take the sample. Make sure that you do not remove or rinse out the white powder
  3. Disconnect or by-pass water treatment devices such as water softeners and carbon filters (consult the manufacturer’s instructions for the correct procedure)
  4. Remove the aerator and washer from the end of the tap and clean the end of the tap and threads with rubbing alcohol or a mixture of bleach and water. If you are unable to remove the aerator from the end of the tap, put the end of the tap in a container of one part bleach and 10 parts water
  5. Run the cold water tap for three to five minutes
  6. Wash your hands thoroughly with soap and water before you collect a water sample
  7. Unscrew the cap from the water sample bottle. Do not touch the inside of the cap or the neck of the bottle. Also, make sure that you do not place the cap on the counter. If you touch the inside of the lid or the neck of the bottle, the bottle must be discarded. You will then have to use a new water sample bottle and collect a new sample
  8. Fill the bottle with water to the 200 ml line on the bottle and put the cap back on. Do not over fill the bottle. Be sure to clean and disinfect the aerator and washer before putting it back on the tap
  9. Complete the form that comes with the sample bottle. It must be completed in full or your water will not be tested
  10. Keep your sample cold by refrigerating it. When you are ready to drop it off, bring it in an insulated cooler with an ice pack
How do I properly take a water sample The Regional Municipality of York en-US

What do the results mean?

The Public Health Ontario Laboratories test the well water for both coliform and E.coli. Coliforms include bacteria that are found in sewage and animal waste, as well as soil and vegetation. E.coli is found in the digestive systems of humans and animals. If you find E.coli in your well water it is probably from human or animal waste.

Type of Bacterial Count Water Test Result Meaning Follow-up

Total coliform per 100 ml

E. coli per 100 ml



Water is safe to drink

Continue to test your well each spring, summer and fall

Total coliform per 100 ml

E. coli per 100 ml

5 or less


No significant evidence of bacterial contamination

Do not drink the water until resamples results are obtained

Three consecutive samples, taken 1-3 weeks apart are needed to determine the stability of the well water supply.

Total coliform per 100 ml

E. coli per 100 ml

More than 5


Significant evidence of bacterial contamination

Do not drink the water until resamples results are obtained.

May be unsafe to drink. Call York Region Health Connection at 1-800-361-5653.

E. coli per 100 ml

Greater than 0

Unsafe to drink

Human or animal waste contamination

Consult York Region Health Connection at 1-800-361-5653 for information immediately.


EST (estimated)

Unsafe to drink

Unsafe for drinking unless boiled or treated.


O/G (overgrown)

Unsafe to drink

Unsafe for drinking unless boiled or treated.

What do the results mean The Regional Municipality of York en-US

What do I do if my water is unsafe?

If your test result shows bacteria in your well water, do not drink it. Boil or chlorinate your well water before using it or choose bottled or municipal water.

Boiling Well Water

You should boil water for at least one minute. When cool, pour the water repeatedly from one clean container into another. This will rid the water of any strange flavours.

Note: Boiling water only kills bacteria. Chemicals in the water will become more concentrated from boiling. If you are concerned about chemicals in your water, have your water tested at a private lab at your own expense.

A list of private labs is provided by the Ministry of the Environment.

Chlorinating Well Water

Here are the directions for chlorinating water:

  1. Fill a container with one gallon of water (4 litres)
  2. Add a 1.25 millilitres (¼ teaspoon) of unscented liquid household bleach to 4 litres (one gallon) of water
  3. Mix well
  4. Let the water stand for 15 minutes
What do I do if my water is unsafe? The Regional Municipality of York en-US

How do I clear bacteria from my well?

To clear your well of bacterial contamination it is recommended that you inspect, repair, disinfect and flush your well and plumbing system.

The source of the bacteria must be found and corrected in order to fix the problem. Otherwise, the problem will repeat itself. Sometimes a treatment device may be necessary. For chronic problems you may need to get an inspection of your well and plumbing system. Contact a licensed well professional for this and do not enter the well.

All dug wells, standpoints and water from lakes, rivers and streams should be treated by devices to make the water safe to drink. Water from these sources is not protected from being contaminated.

Inspect and Repair

  • Inspect your well and make any necessary repairs (contact Well Aware for information on how to inspect your well and what to look for)
    • If the well cannot be repaired or replaced, water treatment devices may need to be installed. Contact your local Conservation Authority to see if there is any grant money available for repairing or replacing the well
  • Collect and drop off samples again after all work is completed

Disinfect and Flush

  • Disinfect and flush your well and plumbing system, a licensed well installer can inspect the well and help with the procedure
  • Take new water samples for testing three to four days after disinfecting and flushing the system
    • If the test results are good wait one week and test it again. If your results are good after three tests, it is safe to use the water.
    • If there is still bacteria in the water disinfect and flush your well and plumbing system again, then take a new water sample for testing
    • If there is still bacteria in the water after two attempts at disinfecting and flushing the well may need to be replaced. The well and any other wells not being used should be abandoned by a licensed well installer
What to do about the well The Regional Municipality of York en-US

How do I disinfect my well?

A licensed well installer can disinfect the well for you. To disinfect your well yourself, please follow the steps below:

  1. Be sure to have a supply of drinking water available before you disinfect your well, as you will not be able to use your water taps for at least 12 hours
  2. If you have a filtering system, remove the carbon filter so that it does not remove the chlorine from the water
  3. Measure out the amount of bleach you need according the Calculating the Proper Amount of Bleach table below
  4. Ensure that you are using bleach that has 5% to 5.25% chlorine and does not have any additives
  5. Mix the bleach with several litres of water before you add it to your well. See Calculating the Proper Amount of Bleach.
  6. Pour the mixture into the well
  7. Using a garden hose connected to an outside tap, turn on the water and let it run until you can smell the chlorine bleach
  8. Push the hose into the entire well (this will ensure that the well is completely disinfected)
  9. Allow the water to circulate through the system for 5 -10 minutes
  10. Turn off the hose, and remove it from the well
  11. Turn on all cold and hot water taps indoors until you start to smell chlorine, then turn the taps off
  12. Let sit for 12 hours, this will also disinfect the plumbing in the house
  13. After at least 12 hours, use the garden hose to drain the chlorinated water from your water system into a drainage ditch (not a septic system)
  14. Drain the water until you can no longer smell chlorine, being careful not to run the well dry

Calculating the Proper Amount of Bleach

The depth of water in your well will be less than the total depth of the well. For the following calculation, use the depth of water if it is known. If the depth of the water is unknown, use the total depth of the well. The total depth may be found on the well record.

Use the table below to estimate the amount of water in the well and the amount of bleach that is required. Make sure that you use 5.0% to 5.25% unscented household bleach.

Diameter of the Well Casing or Pipe
Volume of Bleach per 10 ft. (3 m) of Water in the Well or Pipe

2 in./5 cm

2 tsp./6 ml

4 in./10 cm

6 tsp./30 ml

6 in./15 cm

12 tsp./60 ml

8 in./20 cm

7 tbsp./100 ml

10 in./25 cm

14 tbsp./200 ml

12 in./30 cm

1 cup/250 ml

24 in./60 cm

4 cups/900 ml

36 in./90 cm

9 cups/2.0 L

Note: 1 cup = 16 tbsp. = 48 tsp.

How do I disinfect my well The Regional Municipality of York en-US

Can I get my well water tested for nitrates?

Public Health Ontario Laboratories no longer test well water for nitrates or sodium. If you want to get your water tested for nitrates and sodium, you can have it tested at a private lab.

A list of private labs is provided by the Ministry of the Environment.

Can I get my well water tested for nitrates The Regional Municipality of York en-US

What could be wrong with my water?

Problem Possible Cause Treatment
Diarrhea or stomach cramps Bacteria, parasites, viruses
  1. Chlorination/filtration method
  2. Ultra-violet systems
  3. Chlorination – injector units

Methaemoglobinemia (blue baby syndrome)


Reverse-osmosis units

High sodium

Salty taste

Naturally occurring

Water softener

Reverse-osmosis units

Scale build-up in kettles and water heaters. Soap scum, bathtub ring.


(hard water)

Water softeners

Red to brown slime in toilet tanks: iron staining; unpleasant taste or odours

Iron bacteria


Rusty black stains on fixtures, laundry

Iron and/or manganese

Filtration; greensand filters; water softeners; chlorination/filtration units

"Rotten-egg" smell and taste

Hydrogen sulphide and/or sulphate reducing bacteria

Chlorination/filtration units; greensand filters; aeration

Water has laxative effects


Reverse-osmosis units



Reverse-osmosis units

Gas-like smell, gas bubbles escaping from water

Gases (methane)

Aeration; activated carbon filters

Cloudy water

Turbidity (clay)

Filters; alum treatment


What could be wrong with my water The Regional Municipality of York en-US

When and where will I get my results?

You can receive your sample results in three ways:

  • Through the mail in five to 10 business days
  • By pick up at 661 University Avenue, 17th floor reception
  • By calling 1-877-723-3426 and entering the PIN number from your sample bottle, or TTY 1-866-828-2238 (for the deaf or hard of hearing)
When and where will I get my results The Regional Municipality of York en-US

Using contaminated water


Adults and teens may shower with untreated water as long as no water is swallowed. Older children could also be given a shower with a hand held shower head, avoiding the face. Younger children should be sponge-bathed instead of bathing in a tub. For brushing teeth, use bottled or boiled water.

Hand Washing

If you have to boil your water and there is no known outbreak of human illness, there is no need for additional hand disinfection with bleach or alcohol solution. If you choose to use an alcohol-based hand disinfectant make sure it contains more than 60% alcohol. Alcohol based disinfectants are widely used in the health care setting after washing hands or in situations when water is not available. 

Cleaning and Disinfecting

Toys should be cleaned and disinfected. If the toys are visibly soiled, wash them first with soap and water and then disinfect with a freshly prepared bleach solution (1/4 cup (about 60 ml) bleach in to one gallon (4.5 litres) of water). Dip toys into this solution and air-dry them. Cloth and plush toys should be washed or dry-cleaned.

Countertops, chopping boards or utensils which have come into contact with raw meat must be washed with soap and hot water first, and then disinfected with a bleach solution stronger than that used for emergency hand disinfection. Mix 60 ml (approx. 1/4 cup) bleach in to 4.5 litres (1 gallon) water for this purpose. Do not reuse or store this solution, make it fresh daily.


If your dishwasher has a hot setting, it safely disinfects dishes. If your dishwasher does not have a hot setting, soak dishes for one minute in a solution of 30 ml (1oz) of bleach mixed with 13.5 litres (3 gallons) of lukewarm water. Let dishes air dry. If you wash dishes by hand, you could use boiled water for washing dishes. Dishes washed in soap and hot water can also be rinsed in boiled water or disinfected with the following bleach solution. Mix 1 oz. (about 30 ml) bleach in to 3 gallons (13.5 litres) of water at room temperature for at least one minute. Let dishes air dry.


Continue doing laundry the way you usually do. If you have to launder sheets heavily soiled with feces, carefully remove as much feces as you can and wash as normal. Use rubber gloves when handling heavily soiled sheets.

Wading Pools

Water that is not safe for drinking should not be used in wading pools. If you do not have a source of potable water for the wading pool consider using an alternate recreational water supply or an alternate recreational facility.

Filtered Water

Filtered water should also be brought to a rolling boil for one minute before drinking or using it for cooking.

Other Water Use The Regional Municipality of York en-US



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Related Resources

Private well owners should also inspect their well annually to make sure it is damage-free and in good working condition.

  • Information on Windfall Ecology Centre’s Well Aware Program for private well assessments is available at
  • For assistance on well decommissioning, visit The Lake Simcoe Region Conservation Authority at 905-895-1281 or


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