Mountain West Regional Reports

How to Winterize Your Irrigation System

Learn how to put your system to bed for the season to avoid the costly damage of freezes

winterize irrigation system
Shutting your irrigation controller to “off” is only the first step in winterization.

When I first moved to Colorado, I learned the hard way about the need to winterize my irrigation system. Never having had a system, I had no idea how it worked or of the maintenance it required. Several hundred dollars later, after the backflow preventer had frozen, I learned my lesson.

How to shut off and drain your irrigation system

If you’ve lived in the Mountain West for any period of time, you know we are notorious for an early freeze warning or snowstorm that is quickly followed by days or weeks of warmer weather, extending the growing season for the many plants that survived the quick burst of winter. In this case, it is important to temporarily protect the system. Fortunately, this is easy to do.

1) Set the irrigation controller to “off.”

2) Turn off the water at the mainline. This is usually found indoors in the basement.

mainline valve shut off
Turn your valve so that it is parallel to the pipe to ensure a mainline shut off.

3) Open all valves on the backflow preventer to let it drain. Do this by turning any screw or valve that is perpendicular to the pipe so that it is parallel to the pipe. Water should drain out.

4) Near the mainline shutoff there should be a line drain. Open that using a bucket to collect the water if needed.

insulated backflow preventer
Your backflow preventer should be covered with something to insulate it.

5) Cover your backflow preventer with an insulating cover, a blanket, or something similar.

6) While they aren’t connected to your irrigation system, make sure any hoses attached to spigots on your home are disconnected so that they don’t freeze.

Taking these steps should get your irrigation system through a temporary freeze. Once the cold snap has passed, you can reverse the process and keep watering as needed.

Consider calling a professional to blow out your pipes

Where you live in the Mountain West will determine when you should permanently winterize your system, which involves following the above steps again. The time to winterize should be right before you start to experience freezing temperatures at night. However, if you missed that, winterizing as soon as possible is better than not winterizing at all. Most irrigation systems in the Mountain West are blown out to eliminate as much water in the lines and sprinkler heads as possible. I highly recommend hiring a professional to do this, as home compressors do not generate enough air pressure to completely empty the system and even small amounts of water can cause serious damage. Take it from me (as I learned many years ago) that the annual expense of this maintenance is well worth it.

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—Michelle Provaznik is executive director of the Gardens on Spring Creek in Fort Collins, Colorado, and the CEO of the American Public Gardens Association.

Photos: Michelle Provaznik

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