Ilenna Tai's
Real Estate Knowledge Center:


Drinking Water Testing (Certificate of Potability for Mortgage Purposes)

The Public Health Laboratories Branch of the Ministry of Health and Long-Term Care provides routine drinking water testing for Ontarians who have their own source of drinking water (e.g. a well) that serves a single household.



The Ministry will provide a certificate of potability for mortgage purposes for the sale of a property. To ensure the smooth completion of real estate transactions, it is important that all parties are aware of the timelines involved with drinking water testing. What do I have to do?

1. Drinking water testing performed by the Ministry requires processing of a sample followed by analysis under specific laboratory conditions. Results are usually available within two business days following receipt of the sample by the laboratory.
2. Test reports are mailed to the return address that appears on the submission form or, if requested, the report can be picked up at the laboratory with photo identification. If the submitter (i.e. the person whose name appears on the submission form) wishes to have the report picked up by another person (e.g. their real estate representative), a waiver must be signed by the submitter. Test reports will not be faxed.
3. To ensure that drinking water testing does not delay the completion of real estate transactions (where a certificate of potability is needed for mortgage purposes), the Ministry suggests that the client submit a sample no later than two weeks prior to the anticipated date of closing. It may be advisable to submit a sample for testing as soon as a property is listed for sale, but it should be confirmed that the interval between testing and closing is acceptable to the lender. For More Information For more information, please contact Sandy Edelsward, Program Coordinator, Drinking Water Testing, Ministry of Health and Long-Term Care at (519) 455-9310 or Sandra.Edelsward@moh.gov.on.ca

For the York region, sample bottles for bacterial analysis of private wells may be picked up and dropped off at the following locations for water testing:
  • Newmarket: Tannery Building, 2nd Floor 465 Davis Drive, Suite 240
  • Markham: Public Health Branch Offices, 4261 Highway 7 East, Suite B6-9 (street level) Unionville
  • Richmond Hill: York Region South Services Centre 50 High Tech Road 2nd Floor
  • Georgina: Georgina Civic Centre 26557 Civic Centre Road Keswick


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