Municipal drinking water system reports required annually in Ontario

Ontario’s Drinking Water Quality Standards (O. Reg. 169/03) under the Safe Drinking Water Act, 2002 outlines the standards for 151 microbiological, chemical, and radiological parameters based on Health Canada’s Drinking Water Quality Guidelines, including:

• Chemical testing
  • Trihalomethane
  • Haloacetic Acids
  • Nitrate and Nitrite
  • Sodium
• Lead testing
  • Lead – Plumbing
  • Lead – Distribution
  • Alkalinity – Distribution
  • pH – Distribution
• Inorganic testing
  • Arsenic
  • Cadmium
  • Mercury
  • Uranium
• Organic testing
  • Benzene
  • Polychlorinated Biphenyls (PCB)

Municipalities that operate a drinking water system must report on it annually:

The owner of a drinking water system shall ensure that an annual report is prepared in accordance with this section.

(3) In the case of the following drinking water systems, the annual report must cover the period from January 1 to December 31 in a year and must be prepared not later than February 28 of the following year:

1. Large municipal residential systems.
2. Small municipal residential systems.
3. Large municipal non-residential systems.
4. Small municipal non-residential systems.
5. Non-municipal year-round residential systems.

Section 11 of O. Reg. 170/03: DRINKING WATER SYSTEMS

Annual report must summarize test results, corrective actions, major expenses

(6) The annual report must,

• (a) contain a brief description of the drinking water system, including a list of water treatment chemicals used by the system during the period covered by the report;
• (b) summarize any reports made to the Ministry under subsection 18 (1) of the Act or section 16-4 of Schedule 16 during the period covered by the report;
• (c) summarize the results of tests required under this Regulation, or under an approval, municipal drinking water licence or order, including an OWRA order, during the period covered by the report and, if tests required under this Regulation in respect of a parameter were not required during that period, summarize the most recent results of tests of that parameter;
• (d) describe any corrective actions taken under Schedule 17 or 18 during the period covered by the report;
• (e) describe any major expenses incurred during the period covered by the report to install, repair or replace required equipment;
• (f) in the case of a large municipal residential system or a small municipal residential system, include a statement of where a report prepared under Schedule 22 will be available for inspection under subsection 12 (4); and
• (g) in the case of a large municipal residential system, small municipal residential system or non-municipal year-round residential system, specify the number of points sampled during the periods described in subsection 15.1-4 (2) or subsection 15.1-5 (5) of Schedule 15.1 to the Regulation, the number of samples taken, and the number of points where a sample exceeded the prescribed standard for lead during those periods.

Section 11 of O. Reg. 170/03: DRINKING WATER SYSTEMS

In 2024, 99.9% of the over 524,000 tests across Ontario conducted met Ontario’s drinking water standards.

Municipalities must provide copies of tests and reports and keep records for 2-15 years

This includes:

• Test results
• Approvals
• Works permits
• Licenses
• Orders
• Annual reports
• Reports under Sch. 21 or 22

(4) The information must be available for inspection by any member of the public during normal business hours without charge,

(a) at the office of the owner or, if the office of the owner is not reasonably convenient to users of water from the system, at a location that is reasonably convenient to those users; and

(b) if the owner is not a municipality but the system serves a municipality, at the office of the municipality.

Section 12 of O. Reg. 170/03: DRINKING WATER SYSTEMS

Municipalities must provide last 2 years’ reports to anyone who requests a copy for free

(7) The owner of a drinking water system shall ensure that a copy of an annual report for the system is given, without charge, to every person who requests a copy.

(8) If a drinking water system is connected to and receives all of its drinking water from another drinking water system, the owner of the system that obtains the water shall ensure that a copy of an annual report for the system from which the water is obtained is given, without charge, to every person who requests a copy.

(9) Subsections (7) and (8) do not apply to an annual report that is more than two years old.

Section 11 of O. Reg. 170/03: DRINKING WATER SYSTEMS

Non-municipal drinking-water (private wells) need better oversight and support: Auditor General

3 million Ontario residents (almost 20% of the population) as well as many businesses
and other facilities that serve six or more seasonal residences or a public facilities such as hotels, restaurants or churches, rely on non-municipal drinking-water supplies.

In 2025, the Auditor General of Ontario reported that some small non-municipal drinking water systems have not been identified, assessed and inspected by Public Health Units (PHUs) overseen by MOH, posing a public health risk.

Studies indicate that less than one-third of the 1.3 million Ontarians that get their water from private wells test their drinking water. Of those who do test their water, 35% of samples test positive for indicators of bacterial contamination.

Free bacterial testing available through Public Health

If you think human or animal waste has entered your well or are concerned about contamination, private well water bacterial test kits are available from your nearest PHO laboratory or public health unit. They will test your water for bacteria contamination (eg. coliforms and E. Coli) for free. To test for chemicals like sulphur or nitrates, contact a  licensed private laboratory.

• Testing and treating private water wells – Ontario.ca
• Well Water Testing (Private Drinking Water) – Public Health Ontario

Ontario does not require municipalities to test for PFAS

PFAS are not regulated under drinking water legislation in Ontario. Ontario’s regulations do not mandate routine testing for per- and polyfluoroalkyl substances (PFAS). Studies link PFAS exposure to cancer, liver damage, immune system disruption, and developmental issues.

In 2017, Ontario developed interim advice for PFAS, recommending that drinking water used for human consumption not exceed 70 ng/L for the sum of 11 different PFAS, but this was only applied and tested for where PFAS had been detected in water.

In 2018, the Government of Canada provided the Guidelines for Canadian Drinking Water Quality for Perfluorooctanesulfonic acid (PFOS) and Perfluorooctanoic acid (PFOA).

On August 9, 2024, the Government of Canada withdrew those guidelines and introduced the Drinking Water Objective of 30 ng/L (nanograms per liter) for a sum of 25 PFAS. Canada does not yet have federal PFAS limits.

For comparison, the EU’s recast Drinking Water Directive (DWD) (EU) 2020/2184 limits total PFAS in drinking water to 0.5 µg/L (500 ng/L) and levels for 20 individual PFAS to 0.1 µg/L.

Ontario’s Ministry of the Environment, Conservation and Parks is reviewing the basis of Health Canada’s new objective and will assess the applicability for its use in Ontario and the best way to implement it.

Example reports

• Belleville
• Ottawa
• Port Hope
• Toronto