Reduced Pressure Zone Assembly (RPZ)
A Reduced Pressure Zone (RPZ) Assembly provides the highest level of backflow protection available for irrigation systems, using two independent check valves plus a relief valve that actively vents water to atmosphere if either check valve fails or pressure conditions become unsafe. RPZ assemblies are typically required for high-hazard applications - systems using fertilizer or chemical injectors, or connected to a non-potable source - where a DCVA or PVB doesn't provide sufficient protection. Shop professional-grade RPZ assemblies to protect potable water in your highest-risk irrigation applications.
Reduced Pressure Zone Assembly (RPZ)
An RPZ assembly adds a layer of protection that neither a DCVA nor a PVB provides: an independently operating relief valve positioned between two check valves, which actively vents water to atmosphere the instant it detects a pressure condition that could allow contaminated water to flow backward — rather than relying solely on check valves to hold a seal. This active venting is what makes RPZ the highest level of backflow protection available, and also why it's reserved for the situations where that level of protection is actually necessary rather than installed by default.
High-hazard classification is the deciding factor for when an RPZ is required instead of a DCVA or PVB. Any irrigation system using fertilizer injection, pesticide injection, or other chemical additives introduces a genuine health hazard if that water were ever to flow backward into the potable supply, and most codes classify these systems as high-hazard, requiring RPZ protection specifically. Systems connected to a non-potable water source, like a pond or reclaimed water supply, typically fall into the same category.
Because the relief valve vents water when it activates, an RPZ needs to be installed with proper drainage below it — a floor drain, air gap, or other means for discharged water to go somewhere it won't cause damage or flooding. This is a meaningful installation consideration that doesn't apply to a Double Check Valve Assembly (DCVA) or Pressure Vacuum Breaker (PVB), and it's worth planning for before installation rather than after.
Like other backflow assemblies, RPZ units typically require periodic testing, and given their more complex mechanism, testing and maintenance are often more involved than for a DCVA — check with your local water authority for specific requirements. Parts & Repair Kits cover common replacement components if a relief valve or check valve needs servicing.
The Learn HUB has guides for understanding hazard classifications and determining whether your system requires RPZ-level protection.
