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.

  • 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

Device Testing and Inspection Reports

Common Questions

What is backflow?

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.

What is cross-connection?

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.

What is backpressure backflow?

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.

What is back-siphonage and its causes?

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.

What is a cross-connection control device?

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.

Who is responsible for testing a cross-connection control device?

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

What are the consequences for failing to comply with the testing or installation requirements?

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

Can a time extension be granted to arrange for installation/testing of a cross-connection control device?

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

What are some of the typical types of cross-connections?

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

Will a cross-connection control device affect my water pressure?

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.

Is a plumbing permit required when installing a cross-connection control 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.

What type of reference material is available?

  • 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

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