A plumber is asked to install a backflow prevention assembly on a lawn irrigation system connected to the potable water supply. The system includes underground heads and is subject to back-siphonage and back-pressure. Which type of device would generally provide the necessary protection?

Question: A plumber is asked to install a backflow prevention assembly on a lawn irrigation system connected to the potable water supply. The system includes underground heads and is subject to back-siphonage and back-pressure. Which type of device would generally provide the necessary protection?

Answer options:

• Air Gap
• A hose connection vacuum breaker ✅ A pressure vacuum breaker (PVB)
• A dual check valve

Correct answer: A pressure vacuum breaker (PVB)

Explanation: For irrigation systems, where there's a risk of back-siphonage (due to negative pressure) and potential back-pressure (e.g., from a pump or elevation changes), a Pressure Vacuum Breaker (PVB) is commonly specified as it protects against both, provided it's installed above the highest point of irrigation. An air gap is ideal but often impractical for irrigation; a hose connection vacuum breaker is for a single hose; and a dual check valve only protects against back-pressure, not back-siphonage effectively in all scenarios.