Underground sprinkler systems make it easy to water your lawn in the summer months. Gone are the days of dragging out hoses, setting up sprinklers, and then moving them around to reach your entire yard. However, with an underground sprinkler system, you now have a little extra maintenance to do on the system versus just rolling up hoses when the lawn is watered. Before the winter cold moves in, you need to drain out the water in your sprinkler lines. If left in the lines, the water will freeze and expand, causing the pipes to split and crack. These can be costly repairs, so it is essential to winterize sprinkler systems.
Turn off the water to the sprinkler system. Do this by turning off the master shut-off valve. This is usually located in a basement, crawl space or utility room.
Drain the system manually. There will either be a hose bib or a drain on the backflow preventor. Use a bucket to catch the drained water so that it does not get everywhere.
Attach your air compressor to the drain that you drained the water out of. Make sure all other drains and the master control valve are closed before doing this. You may need to purchase fittings to adapt the air compressor to the drain connection. The fittings needed will vary depending on your setup, and they can be purchased at your local hardware store.
Plug the air compressor in and turn it on. Let it pressurize completely until it automatically shuts off.
Set the pressure regulator dial on the air compressor to 60 PSI. Anything over this can damage your sprinkler system.
Turn each zone on manually to blow the water out of the system. Start with zone the farthest away and work toward the nearest zone. It is time to switch to the next zone when you no longer see mist coming from the sprinkler heads.
Turn off the air compressor and disconnect it. Open all drain valves and leave them open throughout the winter.