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How to Winterize Your Irrigation System

Home Depot
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Learn how to winterize your irrigation system ll The Home Depot Garden Club

Learn how to winterize your irrigation system. Wherever the frost level reaches below the depth of irrigation systems, winterizing can help prevent damage from freezing and ward off costly repairs come next spring.

Water left in the pipes of your irrigation system can freeze over winter, causing damage. Particularly if you live in a region where frost penetrates the ground deep enough to reach those pipes, you owe it to yourself to make an annual habit to winterize your irrigation system when you’re done watering for the year.  

There are three basic methods for draining leftover water from your irrigation system. Which method you should use will depend on the type of irrigation you have in place. If you’re not sure, or don’t feel comfortable winterizing yourself, connect with a professional and have them take a look at your system.

Manual valves

Some irrigation systems are equipped with manual drainage that allows you to empty excess water from the system by simply opening a valve. If you have such a system, shut off the supply of water to the system, then look for the manual valves at the ends and low points of the piping. Open all of the valves and drain the water from the system, including the backflow device.

Some sprinklers are equipped with devices, called check valves, that only allow water to flow one way. If your system is equipped with check valves, you likely need to raise the sprinkler heads in order to let water drain out of those mechanisms. Once you’ve drained the entire system, close all of the valves.

Automatic valves

Other irrigation systems are equipped with valves that will automatically drain water out of the pipes if pressure falls below a certain number of pounds per square inch. These can be activated by turning off the water supply and briefly running one of the sprinkler heads to relieve the water pressure in the system. You may still need to drain the water between the shut off valve and the backflow device. If the sprinkler heads are equipped with check valves, you will need to empty those separately.


The final 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.

For this method you’ll need:

Shut down the water supply and connect the air compressor to the irrigation system using the coupler. Be careful to avoid blowing compressed air directly through the backflow device. Find the sprinkler station highest and farther from the compressor and turn it on. Close the backflow valves. Then slowly open the valve on the compressor, adding more air pressure gradually so that you can cut off the air supply quickly if needed. Do not exceed 80PSI and do not stand near an active head when blowing out your irrigation system.

You should see a spray of water from the active irrigation head. Starting with the furthest and working your way closer to the compressor, activate each irrigation head in turn. Shut them off again when the spray of water ends. When you’ve finished all of the irrigation heads, disconnect the compressor and release any remaining air pressure from the system. Open and close the valves on the backflow device to release any pent up air pressure there as well.

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