How to Reset an Irrigation Backflow Preventer

Turn each of the two ball valves on the side of the backflow preventer clockwise 90 degrees to shut off the flow of water to the device.

Turn the top cap on the backflow preventer counterclockwise until it unscrews from the body.

Identify and remove the poppet and bonnet, small plastic parts that sit inside the body of the backflow preventer.

Press down on the metal retaining clip, and turn it clockwise until it pops free from the tabs inside the backflow preventer. Pull the clip and the spring under it out of the backflow preventer.

Inspect all removed parts for signs of wear. Any cracked, bent or worn parts must be replaced.

Replace the parts in the reverse order that you removed them, substituting new parts for any found to be damaged.

Replace the O-ring that lies around the top of the backflow preventer if it appears to be worn or frayed.

Place the cap on top of the backflow preventer, and turn it clockwise until it is tight.

Remove the rubber caps from the two test valves on the side of the backflow preventer. Use a flashlight to look into the openings on each valve. Make sure each valve is in the closed position. Close any open valves by turning the screw on the side of the valve with a screwdriver. This is critical, as a backflow preventer will not work with the valves even slightly open.

Replace the rubber caps on the test valves. Turn the ball valves on the backflow preventer 90 degrees counterclockwise to return water flow to the device. Water may spray from the top of the cap for a few seconds while the system charges. This is normal and should stop after a few seconds.