Backflow in a drinking water system is when normal water flow to a customer’s property is interrupted and the flow reverses direction. This can happen by accident through hazardous connections to the water pipe system, known as a cross connection.

A cross connection is a water line connection between a drinking water system and any source of potentially contaminated water. Areas where cross connections can occur include:

  • Secondary water supplies (pond water)
  • Cooling towers
  • Fire sprinkler systems
  • Boiler systems
  • Laboratory equipment (medical and industrial)
  • Lawn irrigation systems
  • Solar heating tanks
  • Swimming pools
  • Water re-circulating systems
  • “Green” building systems or ECO friendly
  • Processing tanks

Why is Backflow a Problem?

When backflow occurs, contaminates such as chemicals, pathogens and non-drinkable water may be drawn back into the City water supply system contaminating water people drink.

This hazardous situation can be avoided with the proper installation of a backflow prevention device. Installation is relatively inexpensive and is necessary to safeguard our drinking water supply.

Backflow diagram

Backflow Prevention By-law

The City of Greater Sudbury’s Backflow Prevention By-law requires the installation and regular maintenance of backflow prevention devices within the City. You must comply with the Backflow Prevention By-law if you are:

  • An Industrial/Commercial/Institutional (ICI) customer
  • A high risk residential property owner in the City of Greater Sudbury

If you are unsure if this applies to you, please see our Backflow Prevention By-law.

Backflow Prevention Forms

To comply with the Backflow Prevention By-law, complete the following at your own expense:

Information Request

Complete an information request form for your property identifying the owner of the system.

Cross Connection Control Survey

Complete a cross connection control survey of the water system on your property. This survey must be completed by an authorized professional and updated once every five years or whenever there is a significant change in property use.

Annual Device Testing

  • Have your backflow prevention device(s) tested each year by a qualified professional and submit these records to the City. Testable backflow devices include: double check valve assemblies, reduced pressure assemblies and pressure vacuum breakers and more.

  • Register all your backflow prevention devices with the City and get a certified inspection tag before installation. You can get the inspection tag from the Compliance office by emailing

Make Regular Upgrades

Make regular upgrades, replacements, and/or repairs to any backflow prevention devices and submit the records to the City.

All forms/reports related to the Backflow Prevention By-law must be completed and endorsed by the qualified professional and the property owner before you submit them to the City.

To request any form please contact call 311 or email

How to Choose the Appropriate Backflow Prevention Device

Consult with a qualified plumbing contractor to determine which backflow prevention device is appropriate for your property. Backflow prevention devices must meet the Canadian Standards Association approval.

Installers and testers of Backflow Prevention Devices must hold and maintain a certification issued by the Province of Ontario. The following is a list of "Qualified Persons" who are registered with the City of Greater Sudbury:

  • Al's Plumbing 705-670-0400
  • Lavallee Mechanical Services 705-693-9475
  • Mr. Rooter (Sudbury) 705-521-1398
  • Patrick Mechanical 705-692-3984
  • Wadatek Solutions 705-806-9232
  • Metal-Air Mechanical Systems Ltd. 705-897-2526
  • Mr.Pipes Plumbing and Heating 705-822-2022
  • Castle Plumbing & Heating 705-671-8014
  • Greater Sudbury Plumbing, Heating & A/C 705-806-7473
  • ProActive Water Solution 877-535-2837
  • Percy Witherell Plumbing & Heating Ltd. 705-523-7436
  • Green Truck Plumbing and Renovation 705-410-1090
  • Mid North Automation 705-692-9577

What Is Your Responsibility?

  • You are responsible for complying with the City’s Backflow Prevention By-law.

  •  All plumbing work and inspections, including cross connection surveys, backflow prevention device installation, testing and maintenance must be conducted by a qualified person.

  • Use the list of "Qualified Persons" that are Certificated to perform these tasks.

  • The installation of a backflow device requires a plumbing permit under the Building Code. Your plumber (Qualified Person) must contact Building Services to obtain a permit. Depending on the type and classification of the building, a mechanical engineer and/or submission of the Cross-Connection Control Survey to Building Services may be required. The installation of the device must be done in accordance with the conditions of the permit issued. Please contact the City's Building Services Department at (705) 674-4455 ext. 4278 for additional permit information.

Compliance Is Mandatory

  • The Backflow Prevention By-law is administered and enforced by Water/Wastewater Compliance Services. 

  • Compliance Officers are authorized to enter, inspect, monitor and obtain records from ICI facilities and residential properties within the municipality. 

  • The Compliance Officers can also provide assistance and information to you about backflow prevention to help you comply with the by-law.

  • Failure to comply with the By-law may result in legal action and fines issued. It is every property owner’s responsibility to ensure compliance with the By-law.

  • Customers who do not comply may be fined between $10,000 and $20,000 per day, while Corporations are liable for a fine between $50,000 and $100,000 per day.

Learn more

To learn more about the City of Greater Sudbury’s Backflow Prevention By-law call 311 or email