Start with the hazard, not the acronym

The correct device begins with what could enter the drinking-water system and how reverse flow could occur. The consequences of a cross connection, the presence of backpressure and the plumbing arrangement all affect device selection.

A tester can identify an installed assembly and measure its performance. Selecting or changing the protection for a connection may require a qualified designer, permit and municipal approval.

RPZ: reduced pressure principle assembly

An RPZ has two independently acting check valves with a hydraulically operated relief zone between them. The relief valve can discharge during normal testing or when the zone responds to a fault, so drainage and freeze protection matter.

RPZ assemblies are commonly associated with higher-hazard applications. They need adequate clearance for service and a location where relief discharge will not damage the building.

DCVA: double check valve assembly

A DCVA contains two independently acting check valves with test cocks and shutoffs. It does not have the relief-valve discharge found on an RPZ.

That simpler appearance does not make it a universal substitute. The local authority and applicable standard determine whether a double-check assembly provides acceptable protection for the connection.

PVB: pressure vacuum breaker

A PVB combines an air inlet and a check valve to protect against backsiphonage. It is familiar on many irrigation systems and must be installed above the downstream piping and outlets by the required amount.

A PVB is not intended to protect against backpressure. Enclosures, landscaping and later piping changes can also compromise its required position or access.

Why identification matters at booking

The type, size, location and serial number determine the testing procedure and help match the result to the municipal record. A clear photo of the complete assembly and its data plate is usually more useful than a guess.

Send photos with the City notice when requesting a quote. That allows the provider to plan access, equipment, reporting and any coordination before arrival.

Official sources

Municipal procedures change. Use these sources and the latest property notice as the final authority.

City of Surrey Cross Connection StandardsCity of Chilliwack Cross Connection Control FAQ