Which device is commonly used to prevent backflow into the potable water supply in irrigation systems?

• A. Pressure vacuum breaker.
• B. Check valve.
• C. Flow sensor.
• D. Controller.

Answer: (A)

Preventing backflow into the potable water supply is essential because irrigation can introduce contaminants like fertilizers or pesticides. A pressure vacuum breaker is designed to block that backflow by using a check valve plus a vented air-break. If pressure in the irrigation line drops or siphonage occurs, the vent allows air in and prevents water from flowing backward into the supply. This combination gives reliable protection against both back-siphonage and backpressure, which is why it’s commonly chosen for irrigation systems. A simple check valve alone doesn’t provide the same protection, and flow sensors or controllers don’t address backflow at all.