CSLB C-27 Landscaping ContractorIrrigation SystemsMedium
A landscape contractor is installing a new irrigation system for a large park with multiple zones and a significant distance between the water source and the furthest zones. The design requires a master valve at the point of connection to the potable water supply. What is the primary benefit of installing a master valve in this type of irrigation system?
- AIt automatically adjusts watering schedules based on weather conditions.
- BIt provides an additional layer of protection against water loss from a broken mainline or open zone valve.
- CIt allows for individual zone pressure regulation.
- DIt prevents backflow into the potable water supply.
Show answer & explanationAnswer & explanation
Correct answer: B. It provides an additional layer of protection against water loss from a broken mainline or open zone valve.
A master valve acts as a secondary shut-off for the entire irrigation system. Its primary benefit is to provide an additional layer of protection by closing off the mainline when no zones are active, preventing significant water loss in case of a mainline break or a stuck-open zone valve.
Why the other options are wrong
- A. Automatic watering adjustment based on weather is a function of smart controllers (ET controllers), not the master valve.
- C. Individual zone pressure regulation is managed by pressure regulating valves (PRVs) at each zone or sprinkler head, not the master valve.
- D. Backflow prevention is handled by a dedicated backflow preventer (e.g., RPZ, PVB), not the master valve.
Master Valve
A normally closed valve installed at the beginning of the irrigation mainline, downstream of the backflow preventer, which opens only when any zone valve is activated.
- Acts as a 'main switch' for the irrigation system
- Prevents water loss from mainline breaks or leaking zone valves
- Protects the mainline from constant pressure
- Required by some local codes for commercial systems
Memory trick: Master Valve: The 'Master Switch' that prevents a watery ditch.