What is the minimum backflow prevention required for residential irrigation?

The minimum backflow prevention required for residential irrigation systems is the pressure vacuum breaker (PVB) or a double check valve assembly (DCVA). Both of these devices serve to protect the potable water supply from contamination that could occur due to backflow.

A pressure vacuum breaker is designed to automatically prevent the backward flow of water that can happen due to a drop in pressure in the supply line. If the pressure drops significantly, the internal mechanism of the PVB opens to allow air into the system, thereby breaking the siphon effect that could draw potentially contaminated water back into the potable supply.

On the other hand, a double check valve assembly consists of two independent check valves that are installed in series. This configuration provides an effective barrier against backflow, ensuring that even if one valve were to fail, the second check valve would still provide protection.

The other options, while they have their own applications, do not meet the minimum requirements for backflow prevention in a residential irrigation context. An atmospheric vacuum breaker is often considered less reliable than a PVB or DCVA and is not suitable for constantly pressurized systems. A reduced pressure zone device offers higher protection levels but is typically required in more complex or high-risk systems. An inline filter, while useful for trapping