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Backflow Prevention

Backflow Prevention – Building Permit Requirements

On April 1, 2017, Region of Peel Council passed the Backflow Prevention By-law 10-2017. The purpose of the By-law is to prevent backflow into the Municipal Drinking Water System of The Regional Municipality of Peel for provisions of clean and safe drinking water.

Backflow prevention devices are required under the authority of the Region of Peel By-law 10-2017 and the Ontario Building Code. For further information on By-law 10-2017 and the Backflow Prevention Program, please visit

The following information is required to be provided upon applying for the installation of a backflow prevention device:

  • Backflow prevention device valve specification with reference to the applicable CSA B 64 Standard,
  • Site plan of the building that shows the location(s) of the proposed backflow prevention device(s), and
  • Detailed drawing(s) that indicate:
    • Installation methods of the backflow prevention device,
    • Expansion tank details complete with sizing calculations, a certified thermal expansion relief valve with reference to the applicable CSA Standard, or other method as deemed acceptable by the Authority Having Jurisdiction,
    •  Whether the proposed backflow prevention device(s) will be installed on a water supply system that serves a sprinkler system. Where this occurs, shop drawings and hydraulic calculations are required. For existing sprinkler systems with existing backflow preventers installed (built in) and/or for replacement or repairs only, hydraulic calculations are not required.
  • Completed Commitment to General Review form, which can be accessed from the Forms Centre

Note, the drawings must be sealed, signed, and dated by a Professional Engineer.

The above information must be submitted through the City of Mississauga’s ePlans system, which can be accessed from the following link: For further assistance in applying for a building permit, please call 311 or email