Learn about the various types and protection methods for backflow preventers.

To control any cross connection exists in the facility’s plumbing system, the property owner must have a backflow preventer installed and tested annually.

A certified plumbing contractor with a valid business license will help you select and install the backflow preventer based on the hazard level and in accordance to the City's Specifications and Standards.

An air gap or testable backflow prevention assembly is required for severe hazard cross connection that pose a high health risk.

Installation Locations for Backflow Preventers

Premise isolation: A backflow preventer installed at the entrance of a property/facility. All facilities, except for single family dwelling, must have a backflow preventer, matching the hazard degree, installed on the main domestic water supply, located after the water meter. This protects the municipal water system from potentially becoming contaminated from private piping systems, frequent plumbing alterations and/or other processes happening in facilities.

It is important to protect the backflow preventer from freezing conditions. Insulation must be removable to allow for testing and repair. A freeze protection valve is recommended for irrigation systems or piping prone to freezing, etc.

Internal isolation: A backflow preventer installed inside a property/facility. This protects the occupants from drinking contaminated water, caused by cross connections in the facilities plumbing system. For example, a make-up line to a boiler heating system containing a corrosive chemical agent.

Thermal Expansion consideration: Make sure to have your air release valve inspected on your water heating system(s) before you have a backflow preventer installed on your heating system. As heated water can expand in your tank, this confirms that your tank will operate safely without having possible damage. 

For more information on cross connections and backflow, contact the Engineering Department at engwebmail@surrey.ca.