CSLB C-27 Landscaping ContractorIrrigation SystemsEasy
A landscape contractor is designing an irrigation system for a new commercial building's landscape. The local water authority mandates the installation of a Reduced Pressure Principle (RPZ) backflow preventer. Where in the irrigation system should this device be installed to comply with regulations and ensure proper protection?
- AOn the main line, immediately after the point of connection to the potable water supply.
- BWithin the valve box of the furthest irrigation zone for easy access.
- CDownstream of the zone valves, protecting individual zones.
- DAt the highest point in the irrigation system to prevent siphoning.
Show answer & explanationAnswer & explanation
Correct answer: A. On the main line, immediately after the point of connection to the potable water supply.
RPZ backflow preventers are critical for protecting the potable water supply from contamination. They must be installed on the main irrigation line immediately after the point where the irrigation system connects to the municipal water supply, before any other components, to provide comprehensive protection.
Why the other options are wrong
- B. Placement within a valve box of a specific zone does not provide system-wide backflow protection for the potable supply.
- C. Installing downstream of zone valves would leave the main line and other zones unprotected from backflow.
- D. While elevation can impact backflow, the primary placement rule for an RPZ is at the point of connection, not necessarily the highest point.
RPZ Backflow Placement
A Reduced Pressure Principle (RPZ) backflow preventer must be installed immediately downstream of the potable water connection to an irrigation system.
- RPZ protects potable water from irrigation system contamination.
- Required by code for commercial and high-hazard residential systems.
- Must be located at the point of connection, before any other irrigation components.
Memory trick: Backflow's guard, at the start, protects the home, keeps water apart.