Winterizing Your Sprinkler System

Do not let the recent warm weather fool you.  Winter is just around the corner!  As you mow your lawn for the final time and put away all your garden tools for the season, it is time to think about winterizing your sprinkler system. Wherever the frost level reaches below the depth of irrigation systems, winterizing your system can help prevent damage from freezing and ward off costly repairs come next spring.

Shut Off Water Supply

Broken Irrigation Backflow Preventer

The first step in sprinkler winterization is to shut off the water supply to your sprinkler system completely so that there is no longer even a trickle water flowing. The goal of sprinkler winterization is to make sure the pipes are completely dry. Any remaining moisture might freeze and damage your system. If you have an automatic sprinkler system, make sure to reprogram or shut down the controller. You may need to re-program your settings later on if you completely shut off your controller, but it is well worth the time. Some sprinkler systems have a rain-mode in the system, which shuts off signals to the valves without losing your controller settings.

Drain the System:

Frozen Sprinkler
Any water left over in your sprinkler system and pipes may freeze and expand during the cold winters. A gallon of water when frozen will expand to 9% more than its original volume. This could break the pipes. It is important to remove any water from your sprinkler system.

If you have a system with manual valves, open all the valves and drain the water from the system, including the backflow device. If your sprinkler system has check valves, you may need to raise your sprinkler heads to drain the water out. Close all the valves once the entire system has been drained.

If you have valves that are equipped to automatically drain the water, briefly run one of the sprinkler heads after you have turned off the water supply. This will relieve the water pressure in the system. You still may need to manually drain the shut-off valve, backflow device, and check valves as well. 

Another method is to force compressed air through the irrigation system to discharge excess water through the sprinkler heads. This method is potentially hazardous, both to the wrong types of irrigation systems and to anyone who attempts it without taking the proper safety precautions. If you’ve never worked with compressed air or blown out an irrigation system before, save yourself with potential frustrations and repair costs by consulting with a professional first.

Outside faucets:

Frozen Outside Hose-bib
If you irrigate from an outside faucet, remember to disconnect and drain all of your garden hose.  Most modern hose bibs manually drain after they have been turned off, but you can further protect these outside faucets from freezing by turning off the water supply from inside the house.  If an isolation valve is not available, you might also consider installing insulation covers over these exterior faucets.

Outside Faucet Cover Cut-away View