How to Blow Out a Sprinkler System for Winter

Locate the pressure vacuum breaker, which should be above the sprinkler irrigation control box along the side of the house. It's usually made out of brass and sits on two pipes.

Turn off the main water line to the sprinklers by turning the ball valve on the supply pipe. The valve may be located in a basement or crawl space, or it may be located outside and near the pressure vacuum breaker.

Remove the rubber black cap over the bottom of the two air inlet valves on the side of the breaker. The caps prevent water from leaking out of the breaker and are the attachment point for the air compressor.

Insert a 1/4-inch male air compressor adapter into the valve that you removed the black cap from, turning it clockwise by hand until tight. Turn the attachment 1/4 turn with a wrench to tighten the connection.

Open the lid on the irrigation control box to expose the sprinkler valves.

Unscrew the black solenoid on top of the first valve.

Put on protective eyewear. Turn on the air compressor, charging it fully and setting the PSI outlet valve to 50 lbs. per square inch, or psi, for poly pipe systems or 80 psi for systems with PVC pipes. You can identify your type of system by the color of the pipes in the manifold. Black or blue pipes are poly, and white pipes are PVC. Once the compressor is charged, attach the hose to the adapter that you screwed into the pressure breaker. You will hear a rushing sound as air pushes the water out of the first zone. Water should spray from the sprinkler heads until the line is dry.

Remove the hose from the adapter and allow the compressor to recharge.

Tighten the solenoid on the first valve and unscrew the solenoid on the second valve. Attach the hose to the adapter and allow the second zone to blow out. Repeat these steps until all of the zones have been blown out.