National baseline
The National Plumbing Code of Canada (NPC) Part 2 covers cross-connection control and specifies backflow prevention device requirements based on hazard assessment.
Canadian building code question
What are the building code requirements for backflow prevention in Canada?
The National Plumbing Code of Canada requires backflow prevention at every cross-connection based on the degree of hazard, ranging from atmospheric vacuum breakers for low-hazard connections to reduced pressure backflow assemblies (RPBAs) for high-hazard conditions.
Backflow prevention protects the potable water supply from contamination caused by backpressure or backsiphonage. The National Plumbing Code classifies cross-connections by hazard level and specifies the type of backflow preventer required for each condition, from simple air gaps and atmospheric vacuum breakers to testable reduced pressure backflow assemblies.
What to check first
- Every cross-connection must be protected by a backflow prevention device appropriate to the degree of hazard (low or high).
- High-hazard cross-connections (chemical, industrial, or health-related contamination risk) require a reduced pressure backflow assembly (RPBA) or air gap.
- Testable backflow prevention assemblies must be tested at installation and annually by a certified tester in most jurisdictions.
Jurisdiction notes
Provincial variations
Provinces adopt the NPC with varying amendments. Some provinces and municipalities have additional cross-connection control bylaws that go beyond the code minimum.
Municipal water utility
Many municipal water utilities have their own backflow prevention programs with specific device requirements, testing frequencies, and certified tester registries.
Work through it in this order
- Identify all cross-connections in the plumbing system where potable and non-potable systems could interact.
- Classify each cross-connection by the degree of hazard (low hazard for aesthetic concerns, high hazard for health risks).
- Select the appropriate backflow prevention device for each cross-connection based on the hazard classification.
- Verify device installation requirements including orientation, clearances, and accessibility for testing and maintenance.
- Confirm local water utility requirements for testing, certification, and annual compliance reporting.
Common questions
What is the difference between low-hazard and high-hazard backflow protection?
Low-hazard cross-connections may cause aesthetic issues (taste, odor, color) and can be protected with dual check valves or atmospheric vacuum breakers. High-hazard cross-connections risk health contamination and require reduced pressure backflow assemblies or air gaps.
Do residential buildings need backflow prevention?
Yes. Common residential cross-connections include outdoor hose bibs, boiler fill valves, and irrigation systems. The required device type depends on the specific cross-connection and hazard level.
How often must backflow prevention devices be tested?
Testable backflow prevention assemblies must typically be tested at installation and annually. The specific requirement varies by province and municipality.