How to winterize a sprinkler system

Andrew Hard

Prepare sprinklers for winter

A sprinkler system is one of the most convenient, effective ways to keep your lawn healthy year after year. Their “set and forget” nature frees up valuable time, and they can even save you money in the long term by using less water.

They aren’t without downsides, though. As seasons change, freezing water can cause catastrophic damage to sprinkler system pipes, causing them to burst. This can result in an expensive, stress-inducing repair process.

But, thankfully, there are ways to prevent this. Check out our helpful sprinkler winterization guide for tips and tools to keep your lawn intact.  

When to winterize your sprinkler system

After you’ve stopped watering your lawn for the season, keep a close eye on weather forecasts, specifically the low temperatures at night. Once they start to approach freezing, consider either draining your sprinkler pipes or blowing the water out through the sprinkler heads with an air compressor. We recommend winterizing your system at least a week before the first freeze is expected, but the earlier the better.

How to winterize a sprinkler system with a backflow preventer

If your sprinkler system is attached to your domestic water supply, it will utilize a backflow preventer. Backflow preventers allow water to flow in one direction only, preventing drinking water from being contaminated by outside sources. Backflow preventers must be winterized along with the sprinkler system to prevent cold-weather damage.

The best way to do this is with pipe insulation and duct tape. Thoroughly wrap any aboveground backflow preventers or valves, remembering to leave access points for the various valves. Always check manufacturer literature for instructions specific to your model.

How to winterize an irrigation system

A quick and potent way to winterize an irrigation system is by blowing out excess water with an air compressor. This method is potentially hazardous to both you and your sprinkler system, so consult a professional if you’re unsure.

Before the process begins, shut off the main water supply, close both valves on the backflow preventer, and gather your materials. You will need an air compressor, a coupler to attach the compressor to your irrigation system blowout valve, and safety glasses. You may also need gloves to protect your hands from stuck or stubborn valves.

Use your sprinkler timer to open the farthest sprinkler from the compressor and turn it on, raising the sprinkler head up.Attach the air compressor and turn it on. Slowly open the compressor’s air valve, gradually adding pressure until you see a spray of water coming from the active sprinkler head. Do not stand over the head as it discharges.When the water stops, close the air compressor valve and shut off the head with the sprinkler timer. Do not continue to purge the sprinklers after water has stopped flowing through them, as they can heat up and become damaged quite quickly.Repeat this process for each sprinkler, moving closer to the air compressor as you go.Disconnect the air compressor, and open and close the valves on the backflow preventer to release any remaining water or air pressure.Close all the valves for winter and insulate aboveground backflow preventers or valves as mentioned above.

How to winterize an irrigation system without an air compressor

If you don’t have access to an air compressor, fear not — irrigation systems often have manual drainage valves that are extremely simple to use.

As with the air compressor method, turn off the water supply to the system.Locate the manual drain valve or valves, which are likely at the end or at various low points on the sprinkler piping.Drain all excess water from the system. These valves may still be under some pressure, so we still recommend wearing eye protection for your safety. Close the drain valves.Drain water from the backflow device and winterize it per the instructions above.

How to winterize a Rain Bird sprinkler system

Rain Bird sprinkler systems can be purged via manual drainage valves and air compressor blowouts, but they often feature automatic drain valve systems. Rain Bird’s automatic valves essentially do all the work for you, opening via a spring-loaded mechanism. Assuming they are installed properly at low points of the pipe, all you need to do is turn the water supply off and excess water will be drained.

After that, winterize your backflow preventer as needed, and turn your sprinkler timer off. Rain Bird recommends that you leave the unit plugged in, however, as this keeps your set program intact and wards off condensation that could damage the internals. As always, refer to your model’s instructions for specifics.

Andrew Hard is a writer for BestReviews. BestReviews is a product review company with a singular mission: to help simplify your purchasing decisions and save you time and money.

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