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Backflow Prevention

The Town of Grimsby and the Ontario Ministry of Environment's multi-barrier commitment is to enhance the security and protect the residents and other users of Grimsby's drinking water system. The Town of Grimsby has put a Backflow Prevention Program in place to uphold all applicable legislative and regulatory requirements from the Ministry of Environment (MOE).

What is Backflow?

Backflow is the undesirable reversal of flow of non-potable water or other substance through an unprotected cross-connection into the piping of a public water system or consumer's potable water system which could cause harmful contamination of the drinking water.

Purpose of the program

The Backflow Protection Program will help to ensure that the drinking water system is protected against the entry of any harmful contaminants.

Application of the program

The Backflow Prevention Program and By-law are applicable to industrial, commercial, institutional, and multi-unit residential buildings/structures. This is accomplished through the installation of backflow prevention devices at potential sources of contaminants and annual testing of those devices to ensure they are functioning properly.


  • Backflow means the flowing back or reversal of the normal direction of flow of water
  • Backflow prevention device means a device, certified to CSA standard, that prevents backflow
  • Cross-connection means any actual or potential connection between a potable water supply or system and any source of pollution or contamination through which backflow may occur
  • Potable means drinkable water


Review the Town's By-law 09-73 Backflow Prevention for appropriate requirements that apply.

(The Backflow Prevention By-law is available in alternate format, upon request)

  • Cross-Connection Control Surveys to identify the degree of hazard(s) of a building/property
  • Guides for degree of hazard and selection of types of devices
  • Installation of backflow devices, permits, and testing and inspection requirements
  • Licencing and certification accreditation of contractors performing the work and restrictions
  • Compliance and penalties
  • Definitions

Cross-Connection Control Survey Forms

(The backflow prevention reporting forms are available in alternate format, upon request)

Device Testing and Reporting

Testing of your backflow devices is required to be completed yearly by a licensed backflow tester.

The Town of Grimsby has contracted BSI Online to assist with province required cross-connection/backflow tracking requirements. As a device owner, you will receive a letter from BSI and the Town regarding your backflow testing due date. You will need to provide a copy of this letter and/or your Customer Confirmation Number (CCN) to your tester.

Your tester will be required to submit the results of the backflow tests online. For the first year of implementation (starting December 1, 2022), the Town of Grimsby will be covering the administration fee for the filing of test results. After the first year, there is a $17.95 fee for each test that needs to be filed.

As of December 2022, paper copies of test results will no longer be accepted. 

Test Kits and Calibration - Federal Government Standards

Measurement Canada

Standards Calibration - Mass-Measurement Canada

Submitting Cross Connection Reports

Backflow Cross Connection Control Surveys can be submitted by email to; regular mail; drop box at the front of Town Hall; or by faxing to 905-945-5010

Customer Service

BSI Online will serve as the primary point of contact for the yearly backflow testing program, and can be contacted below:

Common Questions

Backflow is the undesirable reversal of flow of non-potable water or other substance through an unprotected cross-connection and into the piping of a public water system or consumer's potable water system. There are two causes of backflow are back-siphonage and backpressure.

A cross-connection is any temporary or permanent connection between a public water system or consumer's portable water system and any source or system containing non-potable water or other substances through which backflow may occur. An example is the piping between a public water system or consumer's potable water system and a heating or cooling system, fire system or irrigation system, etc.

Backpressure is the reversal of normal flow in a system due to pressure higher than the supply pressure. Backpressure can result from an increase in downstream pressure caused by pumps, temperature increase in boilers, elevated tanks or other pressure producing systems.

Back-siphonage is the reversal of normal flow in a system caused by a negative or reduced pressure (vacuum or partial vacuum) in the supply piping. Back-siphonage can be created when there is an interruption of the water supply due to nearby fire-fighting, repairs or breaks in the water supply mains, etc.

A cross-connection control device is a mechanical device that prohibits backflow of water into the public drinking water system. The principle types of cross-connection control devices are a reduced-pressure principle assembly, a pressure vacuum breaker assembly, and a double check valve assembly. Examples of a secondary type of device are hose connection vacuum breakers and residential dual check valves.

The owner of the property or agent of the owner (i.e.: property manager) or as otherwise identified in the lease agreement.

Failure to comply with the requirements of the By-law may result in disconnection of the water supply to the property.

Yes, however a request for an extension must be made and approved by the Town.

Boilers, fire protection systems, commercial dish washers, high pressure washers, irrigation systems/sprinklers, etc.

Yes, cross-connection control devices can cause some degree of pressure loss. The typical pressure drop across a device depends on the type, make, size and location of the device.

Yes, any plumbing alteration related to the installation of a testable cross-connection control device (RP, DCVA & PVB) will require a plumbing permit. For additional permit information or inquiries, contact the Building Department.

  • AWWA Western Canada Section, Cross-Connection Control Manual
  • CAN/CSA-B64.10.01 Manual for the Selection and Installation of Backflow Prevention Devices
  • EPA's Cross-Connection Control Manual
  • AWWA's M14 Manual

Contact Us

Town of Grimsby
160 Livingston Avenue
Grimsby ON, L3M 0J5
Phone: 905-945-9634
Fax: 905-945-5010

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