Information and rules for owners or operators of systems supplying drinking water to municipalities.
Municipalities own—or have water supplied to them through—various types of drinking water systems. The provincial government, through the Ministry of the Environment, Conservation and Parks, regulates these systems to ensure water safety and quality. This includes: * registering all municipal drinking water systems * licensing system owners/operators * authorizing operators to run and maintain drinking water systems * issuing drinking water works permits to modify, repair or extend drinking water systems
Every owner and operator of a drinking water system must ensure that: * the system’s water meets Ontario’s Drinking Water Quality Standards * anyone who operates or works on their system is properly trained and licensed * drinking water tests are done by licensed, accredited laboratories * adverse test results are reported to the Ministry of the Environment, Conservation and Parks and the local medical officer of health
Provincial standards for water quality are set out in: * Safe Drinking Water Act, 2002 * Ontario Regulation 169/03 (Water quality standards) * Ontario Regulation 170/03 (Drinking water systems)
There are 4 types of municipal drinking water systems:
Serve 100+ private residences.
Serve 6 to 100 private residences.
Supply water to designated facilities (e.g., day cares, schools, hospitals) at a rate greater than 2.9 litres per second.
Supply water to designated facilities (e.g., day cares, schools, hospitals) at a rate less than 2.9 litres per second.
An accredited operating authority must be in charge of a municipal residential drinking water system at all times. To be accredited, you must establish and maintain a quality management system that meets the requirements of Ontario’s Drinking Water Quality Management Standard (DWQMS). Accreditation is granted after a third party verifies that your quality management system meets the requirements of the DWQMS.
If you have questions about accreditation or would like to become accredited to the DWQMS, please contact one of these organizations: AET Group Inc * Email: dwqms@aet98.com * 519-576-9723 * Toll-free: 1-877-876-9235
Intertek * Email: business.assurance@intertek.com * Toll-free: 1-800-810-1195
NSF-ISR Canada (NSF) * Email: nsfcanada@nsf.org * Tel: 519-821-3334 (835: 519-821-3334) * Toll-free: 1-866-261-0086 * Toll-free: 1-800-361-7525
Learn more: Ontario’s Drinking Water Quality Management Standard – Pocket Guide Learn more: Accreditation Protocol – Operating Authorities Learn more: Director’s Directions – Minimum Requirements for Operational Plans Learn more: Operating Authority Accreditation: How to respond to audit findings
Municipal residential systems must be licensed under the Municipal Drinking Water Licensing Program. Licences are valid for 5 years as long as you: * maintain your status as (or employ) an accredited operating authority * prepare a financial plan and have it approved by your municipal council * have a valid permit to take water * operate your drinking water system according to the conditions in your licence
To apply for or amend a licence: 1. Refer to the Guide for Applying for DWWP Amendments, Licence Amendments, Licence Renewals and New System Applications. 2. Complete the application. 3. Submit form and requiring supporting information by email to: MDWLP@ontario.ca.
To renew a licence: 1. Contact the municipal water and wastewater permissions section at MDWLP@ontario.ca to obtain a copy of the application form and Guide to Supporting Information Required for a Municipal Drinking Water Licence renewal. 2. Submit form and required supporting information by email to MDWLP@ontario.ca.
Download: Guide to applying for amendments, licence renewals and new systems Download: Application to apply for a new licence, amend or renew a licence Get a permit to take water Learn more: financial plans for drinking water systems (part II sec. 13 to 14)
Call or email the approvals and licensing help line: * Tel: 416-314-4300 * Toll-free: 1-888-999-1305 *
Monday to Friday 9:00 a.m. to 5:00 p.m.
Operators must register drinking water systems and keep information up to date. To register: 1. Complete the Drinking Water System Profile Information form * email the completed form to: waterforms@ontario.ca 2. Complete the Laboratory Services Notification form (when you receive your Drinking Water System Number) * fax the completed form to: 416-314-8716
Download: Drinking Water System Profile Information form Download: Laboratory Services Notification Form
Download: Drinking Water System Profile Information form
To make any additions, modifications, replacements or extensions to your drinking water system, changes must be either approved through a Schedule C amendment to your drinking water works permit or pre-authorized through a condition in your drinking water works permit. Director Notification is required within 30 days of completing or placing the alteration into service if: * a pre-authorized alteration will change the description of a drinking water system component in your drinking water works permit * the alteration was approved through a Schedule C amendment
To notify the Director: 1. Complete the Director Notification Form. 2. Submit form by email: MDWLP@ontario.ca.
Download: Director Notification form Learn more: Watermain disinfection procedure
The Director does not need to be notified of any repairs, maintenance or modifications that are exempt from the approval requirements.
To make an alteration or modification that has not been included as a preauthorized condition, you will need to amend your drinking water works permit (DWWP). To amend your permit: 1. Refer to the guide to amend your drinking water works permits. 2. Complete the application to amend your drinking water works permit. 3. Submit form and supporting information by mail to: * Director, Safe Drinking Water Act—Part V * 135 St. Clair Ave. West, 1st Floor * Toronto, Ontario M4V 1P5
Download: Guide to amend drinking water works permits Download: Application form to amend drinking water works permits
To request permission to fragment your system or to obtain relief from regulatory requirements, first read the guide below and then complete and submit the application form. Read: guide for applying for fragmentation and relief from regulatory requirements Download: Application form for fragmentation or relief from regulatory requirements
To take advantage of the conditions preauthorized in your drinking water works permit, complete the form(s) for your records. You are required to keep this record at the drinking water system for a minimum of 10 years. Download: Form 1—Record of watermains authorized as a future alteration Download: Form 2—Record minor modifications or replacements to the drinking water system Download: Form 3—Record of addition, modification or replacement of equipment discharging a contaminant of concern to the atmosphere
Children up to 6 years old are more sensitive to the effects of lead because they are still developing and their bodies can absorb it more easily than adults. Even small amounts of lead can be harmful to young children, infants and pregnant women. Owners and operators of municipal residential drinking water systems must test for lead. You need to take water samples from these 2 sources: * plumbing—pipes inside the home or building * distribution locations—pipes leading to the home or building
You must obtain permission from the owner of the property before testing. Steps: 1. Turn on tap for at least 5 minutes to flush water from lines, turn off. 2. Wait 30 to 35 minutes—do not use plumbing. 3. Put bottle under tap, turn tap on to normal flow rate and take 3 samples continuously without turning off the tap and with as little spillage as possible between samples. 4. Take 1 one-litre sample for lead testing. 5. Take a 2nd one-litre sample for lead testing. 6. Take a 3rd sample and perform pH testing using an electronic pH meter with a sample size per metre specifications.
A distribution sample must be taken on the same day and from a location as close as reasonably possible to the locations where plumbing samples are being taken. Steps: 1. Flush sampling point (hydrant or tap) until you can get a sample from that part of the system. 2. Take 1 sample for lead testing (size identified by the lab conducting the test). 3. Take a sample for total alkalinity (size identified by the lab conducting the test). 4. Take a sample and perform pH testing using an electronic pH meter with a sample size per meter identification.
You can request to reduce your lead sampling requirements. Read: standard and reduced sampling and eligibility for exemption
The owner or operating authority of the system must include the following information in their Annual Report: * number of points sampled * number of samples taken * number of points where a sample exceeded the standard for lead
To request relief from lead sampling requirements read:
Guide for Applying for Relief and Fragmentation from Regulatory Requirements
Download: Application form: Request for regulatory relief from lead sampling requirements
Questions:
Client Services and Permissions Branch
Ministry of the Environment, Conservation and Parks
135 St. Clair Ave. West, 1st Floor
Toronto, Ontario
M4V 1P5
* Tel: 416-314-4300
* Toll-free: 1-888-999-1305
*
In the case of adverse drinking water test results for drinking water systems regulated under the Drinking Water Systems regulation Ontario Regulation 170/03, licensed laboratories and drinking water system owners are required to report as below: * Provide oral notice to Spills Action Centre (SAC) at 1-800-268-6060 or 416-325-3000 and the local medical officer of health. * Provide written notice to SAC and the local medical officer of health within 24 hours of the oral notice. SACs fax number is 1-800-268-6061 or 416-325-3011 * Provide written notice to SAC and the local medical officer of health within 7 days after the issue has been resolved, summarizing the action taken and the results achieved. SACs fax number is 1-800-268-6061 or 416-325-3011
Notice of Adverse Test Results and Issue Resolution (Schedule 16)
Learn more about the establishment, alteration or operation of a drinking water system in these technical bulletins: * Steps to become a "Supervised Person" * Filtration processes * Ultraviolet disinfection * Total trihalomethane (TTHM) reporting requirements * Residual chlorine analyzers * Residential water testing * Laboratory update bulletin: Drinking water testing, Issue 1 * Laboratory update bulletin: Drinking water testing, Issue 2 * Permits to take water * Watermain disinfection procedure
For questions about: * forms * drinking water systems * confirming your system classification * water testing
Call: 1-866-793-2588
Monday to Friday 9:00 a.m. to 5:00 p.m. Updated: May 06, 2026 Published: March 13, 2017 [e.g.]: for example [DWQMS]: Drinking Water Quality Management Standard [DWWP]: drinking water works permit [II]: Two [sec.]: section [Tel]: telephone [V]: five [St.]: saint [Ave.]: avenue [pH]: potential of hydrogen [SAC]: Spills Action Centre [SACs]: Spills Action Centre