Toronto Water treats, stores and distributes over 435 billion litres of safe potable (drinkable) water annually to all industrial, commercial and household water users in the City of Toronto. The division also delivers water to the southern portion of York Region.

Drinking water treatment and supply in municipalities is subject to stringent provincial regulations and standards to ensure that water supplied by the municipal drinking water system is safe to drink

Municipal Drinking Water Regulation in Ontario

In 2000, there was a public health crisis in Walkerton, Ontario, due to the water supply being contaminated as a result of improper water treatment following a heavy rainfall and flooding. Over 2,300 people became sick and seven people died when E. coli and Campylobacter jejuni entered the Walkerton municipal drinking water system. A provincial public inquiry into the incident was undertaken, resulting in 121 recommendations (all of which were implemented by the provincial government).

As a result of the inquiry, the regulation of municipal drinking water systems across Ontario was transformed and it was recommended the Ministry of Environment, Conservation and Parks (MECP) play a key role in overseeing municipal drinking water system regulation. The government passed numerous pieces of legislation including the Safe Drinking Water Act, 2002, to ensure drinking water systems provide good quality, safe drinking water.

Provincial Drinking Water Quality Management Standards

The MECP has the authority to set standards according to the Safe Drinking Water Act, 2002, and ensure municipal compliance to those standards. All water provided by the drinking water system must meet Ontario’s Drinking Water Quality Management Standards (DWQMS). The purpose of the standards is:

  • to facilitate the operating authority’s ability to consistently produce and/or deliver drinking water that meets applicable legislative, regulatory and owner requirements, and
  • to enhance consumer protection through the effective application and continual improvement of a municipal utility’s Quality Management System (QMS).

Provincial Drinking Water Quality Licensing Program

The MECP administers a Drinking Water Quality Management Licensing Program for municipalities and approves licences for the operation of municipal residential drinking water systems. The MECP provides information and rules for owners or operators of municipal drinking water systems and accredits municipalities who meet the requirements of the province’s Drinking Water Quality Management Standards (DWQMS). The program ensures:

  • the water system meets Ontario’s DWQMS
  • anyone who operates or works on the drinking water system is properly trained and licensed
  • drinking water tests are done by licensed, accredited laboratories
  • adverse test results are reported to the MECP and the local medical officer of health

The licence includes:

  • a drinking water works permit
  • a permit to take water (in Toronto, water is taken from Lake Ontario)
  • an approved operational plan based on the DWQMS
  • accreditation by a third-party audit of the City’s Quality Management System provisions
  • an approved financial plan

Toronto Water’s Drinking Water Quality Management System

To ensure Toronto’s drinking water system meet’s Ontario’s Drinking Water Quality Management Standards (DWQMS), Toronto Water has developed its own Quality Management System (QMS) for drinking water. The QMS is a collection of business processes focused on achieving policies and objectives to meet provincial and federal legislative and regulatory requirements.

Toronto Water completes QMS re-accreditation audits every three years. For more than a decade, Toronto has consistently achieved perfect scores in meeting provincial standards and requirements for drinking water quality.


To maintain Toronto’s high quality tap water, the City has a strict monitoring program that includes regular sampling, testing and reporting. Details can be found in these reports submitted to the Ministry of the Environment, Conservation and Parks.

Drinking Water Quality Annual Analysis Summary Reports

2021 Report   I 2022 Report  | 2023 Report

Provides a summary of the parameters found in Toronto’s drinking water, including several microbiological, operational, general physical and chemical, inorganic, organic and radiological parameters.

Drinking Water System Annual Reports

2020 Report   I 2021 Report   l 2022 Report   I 2023 Report

Provides a brief description of each water treatment plant and the distribution system, including the list of treatment chemicals used, capital projects, summary of testing and any adverse results reported to the Ministry of the Environment, Conservation and Parks.

Drinking Water System Summary Reports

2020 Report   I 2021 Report   l 2022 Report   I 2023 Report

Provide information about Toronto’s drinking water system, including accreditation, site inspections by the Ministry of the Environment, Conservation and Parks, compliance with all regulations and a summary of water produced at each filtration plant.

Drinking Water Quality Management System Operational Plan

The Operational Plan outlines the processes and procedures for the overall quality management of the drinking water system to ensure the provision of safe drinking water, compliance with all regulatory requirements and continuous improvement of the system. If you would like to view the Operational Plan for City of Toronto’s Drinking Water Quality Management System, please contact

Drinking Water System Financial Plan


Provides information on the Toronto City Council-approved, five-year financial plan for Toronto’s Water System, including recommended service levels, performance measures, operating and capital budgets, water and wastewater rates and service fees, and related Council-decision documents.

Lead in Drinking Water Mitigation Strategy – Annual Report

2020 Report   I 2021 Report   I 2022 Report   | 2023 Report

Provides an annual update on the City of Toronto’s Lead in Drinking Water Mitigation Strategy. In 2011, Toronto City Council approved the Lead in Drinking Water Mitigation Strategy, a comprehensive strategy comprised of corrosion control, replacement of lead water services, lead testing, a faucet filter program, and public education to reduce lead in drinking water.