Backflow Preventer Testing Calgary — Annual RPZ Testing Requirements and Repair Guide

Calgary irrigation systems require annual backflow preventer testing to comply with the City of Calgary cross-connection control bylaw. The RPZ (Reduced Pressure Zone) backflow preventer installed on every Calgary irrigation system must be tested by a City-certified tester each year. J.G. Irrigation coordinates annual backflow preventer testing for all clients. Call 587-433-4795.

What Is a Backflow Preventer and Why Annual Testing?

A backflow preventer is a device installed between your home’s potable water supply and the irrigation system. It prevents contaminated irrigation water from flowing backward into the drinking water supply if supply pressure drops suddenly. In Calgary, the RPZ assembly is the approved backflow preventer type. The RPZ contains two independently acting check valves and a relief valve. The City of Calgary cross-connection control program requires annual testing — each check valve must be confirmed to be holding proper differential pressure.

What Happens During Calgary Backflow Preventer Testing?

• Test cock connection: The tester connects a differential pressure gauge to the RPZ assembly’s test cocks.
• First check valve test: Differential pressure across the first check valve is measured. Pass: 5 PSI minimum.
• Second check valve test: Second check valve differential pressure measured. Pass: 1 PSI minimum.
• Relief valve test: Must open at 2 PSI or less below first check differential.
• Documentation: Results submitted to City of Calgary Water Services.

Calgary Backflow Preventer Failure — What Happens Next?

If the RPZ fails the annual test, repair or replacement is required. Common failure causes: worn check valve seats, debris-fouled seats, and relief valve spring failure. A failed check valve can often be repaired by replacing internal rubber seats and springs — cost $95–$250 — without replacing the entire brass body. A cracked or corroded body requires full replacement ($350–$650 installed). J.G. Irrigation repairs and replaces backflow preventers and coordinates re-testing after repair. Call 587-433-4795 or visit our irrigation maintenance service page.