Where should the isolation valve be installed in relation to the meter and backflow device?

Where should the isolation valve be installed in relation to the meter and backflow device?

• A. Between the meter and backflow device
• B. Before the meter
• C. After the backflow device
• D. On the downstream line after the zone

Answer: (A)

Isolating the backflow device must be done on the supply line that feeds it, so the valve belongs between the water meter and the backflow preventer. This placement lets you shut off water to the backflow assembly for maintenance or replacement without affecting the rest of the service, and keeps the backflow device protected downstream from the meter. Placing the valve before the meter would cut off the entire service, while placing it after the backflow wouldn’t allow proper isolation of the backflow for servicing.

Isolating the backflow device must be done on the supply line that feeds it, so the valve belongs between the water meter and the backflow preventer. This placement lets you shut off water to the backflow assembly for maintenance or replacement without affecting the rest of the service, and keeps the backflow device protected downstream from the meter. Placing the valve before the meter would cut off the entire service, while placing it after the backflow wouldn’t allow proper isolation of the backflow for servicing.