5 Essential Tips to Winterize Your Underground Irrigation System

As autumn leaves fall and temperatures drop, it's time to think about protecting one of your most valuable landscaping investments: your underground irrigation system. Freezing water expands and can crack pipes, burst valves, and ruin sprinkler heads, leading to costly repairs come spring. Proper winterization is the key to ensuring your system survives the cold months and operates flawlessly when warmer weather returns. In this guide, we'll walk through five essential tips that every homeowner should follow to winterize their irrigation system, with a focus on Orbit products and best practices.

Whether you're a seasoned DIYer or a first-time homeowner, these steps will help you avoid common freeze-related damage. From draining the main line to protecting backflow preventers, we'll cover everything you need to know. And with Orbit's reliable components—like durable anti-siphon valves and easy-to-use gear-drive sprinklers—you can trust that your system is built to last, provided you take the right precautions. Let's dive into the five tips that will safeguard your sprinklers all winter long.

1. Shut Off the Water Supply and Drain the Main Line

The first and most critical step in winterizing your underground irrigation system is to turn off the water supply. Locate the main shut-off valve for your irrigation system—typically found in your basement, crawl space, or an underground valve box. Turn it clockwise until it stops. Once the water is off, open a faucet or drain valve downstream of the shut-off to relieve any pressure and allow the remaining water to drain out. If your system includes a manual drain valve, open it fully to let gravity do the work. For extra safety, consider installing a 1 In. FPT Anti-Siphon Valve with Flow Control and 3/4 in Reducer 57604, which features a built-in drain mechanism that simplifies winterization. Orbit's anti-siphon valves are designed with freeze protection in mind, but they still need to be manually drained or blown out in colder climates.

After shutting off the main water supply, don't forget to disconnect any hoses or timers attached to outdoor faucets. If you use a hose-end timer like the Orbit Pro Flo Sprinkler Timer for Hose Watering 62041, remove it and store it indoors for the winter. Electronic components can be damaged by freezing temperatures, so it's wise to bring all removable controllers and timers inside. Once the main line is drained, leave the drain valve slightly open to prevent any trapped water from freezing and expanding. This simple practice can save you hours of repair work next season.

• Always shut off the main valve at the house, not just the zone valves.
• Open manual drains or use compressed air for stubborn water pockets.

2. Use the Blowout Method to Clear Sprinkler Lines

In regions where temperatures consistently drop below freezing, simply draining the system may not be enough. The blowout method uses compressed air to force all remaining water out of the pipes, sprinkler heads, and valves. This is the most effective way to prevent ice damage. You'll need an air compressor (typically 10-20 CFM at 40-80 PSI for residential systems) and an adapter to connect it to your irrigation system. Never exceed the maximum recommended PSI for your pipes—typically 50 PSI for PVC systems—to avoid damaging fittings or blowing off sprinkler heads. Connect the compressor to the blowout port (usually located near the backflow preventer or main shut-off) and begin by opening one zone at a time.

Stand back from sprinkler heads as air and water will spray out forcefully. Continue blowing air until only a fine mist of water appears, then close that zone and move to the next. Orbit's systems, especially those with gear-drive rotors like the Compact Gear-Drive Sprinkler on Metal T Spike 56565, are designed to handle controlled air pressure, but always remove the sprinkler head if you're unsure of its PSI rating. The blowout method is a job best done by a professional if you lack the proper equipment, but many experienced DIYers manage it successfully. Remember to blow out each zone individually, including any drip irrigation lines, which may require lower air pressure (around 30 PSI) to avoid damaging emitters.

• Never run the compressor without a pressure regulator—excess pressure can rupture pipes.
• Blow out zones one at a time, starting with the farthest zone from the compressor.

3. Protect the Backflow Preventer and Valves

Backflow preventers are essential for keeping contaminated water from siphoning back into your home's drinking supply, but they are also vulnerable to freezing. Most backflow devices are installed above ground and contain small amounts of water that can freeze and crack the brass or plastic housing. After shutting off the water, close the ball valves on the backflow preventer, then open the test cocks or bleed screws to drain any trapped water. Leave the bleed screws slightly open for the winter to allow any condensation to escape. If your backflow device is not self-draining, you may need to wrap it with insulation tape or foam covers designed for outdoor faucets.

Orbit's anti-siphon valves, such as the 1 In. FPT Anti-Siphon Valve with Flow Control and 3/4 in Reducer 57604, incorporate a built-in vacuum breaker that should be drained manually. Simply unscrew the cap or open the bleed port after the water is off. Additionally, if you have a valve manifold box, ensure it is free of debris and water. Some homeowners place a bucket or inverted pot over the valves to keep snow and ice away. Orbit also offers manifold accessories that can simplify winterization. For valves in below-ground boxes where water might pool, use a pump or sponge to remove standing water before covering.

• Leave test cocks and bleed screws open just a quarter turn to allow drainage.
• Use protective covers on above-ground backflow preventers for extra insulation.

4. Remove and Store Adjustable Sprinkler Heads

Pop-up sprinklers and rotors are often the most exposed parts of your system. If you live in an area with heavy snow or repeated freeze-thaw cycles, consider removing the sprinkler heads altogether for the winter. This prevents ice from forming inside the nozzle and cracking the body. Orbit's gear-drive sprinklers, such as the Compact Gear-Drive Sprinkler on Metal T Spike 56565, are designed with durable materials, but metal springs and plastic gears can still be damaged by freezing moisture. To remove a head, simply unscrew it from the riser or pop-up assembly. Be careful not to damage the threads or drop dirt into the pipe.

Once removed, rinse the heads with clean water to remove any soil or debris, then store them in a warm, dry location like a garage or basement. If you prefer to leave heads installed, at least adjust them to their highest positions so any water that accumulated inside can drain out. For systems with adjustable patterns, like the 8-Pattern Plastic Turret Sprinkler 58223, set the pattern to a low angle to help water escape. Another tip: mark each head with a label or take a photo of the sprinkler layout before removal so you know exactly where each head goes in the spring. This is especially helpful for systems with multiple head types and arc patterns.

• Store removed sprinkler heads in a labeled plastic bin to keep them organized.
• If leaving heads installed, flush the system briefly after blowout to clear debris.

5. Insulate Exposed Pipes and Valves Above Ground

Any pipe or fitting that remains above ground—such as supply lines running along a foundation wall, exposed risers, or valve boxes—is susceptible to freezing. Insulating these components adds an extra layer of protection. Use foam pipe insulation sleeves (available at hardware stores) that are split to slide over pipes. Secure them with duct tape or zip ties. For valve boxes, you can fill the box with insulating foam sheets or use a specialized valve box cover that blocks wind and snow. Make sure the insulation does not trap moisture, as wet insulation can freeze and cause more harm.

Orbit's PVC fittings, like the 3/4" Slip x MHT PVC Fitting 53361, are durable but can crack if water freezes inside. For any exposed connections, wrap them with insulation tape or use heat tape (electrical tape that generates heat) for extreme climates. Avoid using incandescent bulbs or open flames—they are fire hazards. Also, check that any drain valves you left open are not obstructed by ice or debris. If you live in a particularly harsh winter zone, consider having a backup plan like a remote frost sensor. Orbit's B-hyve smart systems include freeze alerts that notify you if temperatures drop dangerously low, allowing you to take action before damage occurs.

• Insulate all above-ground pipes, not just the backflow preventer.
• Inspect insulation annually for wear or water damage before winter.

Winterizing your underground irrigation system doesn't have to be a daunting task. By following these five tips—draining the lines, using the blowout method, protecting backflow preventers, removing heads, and insulating exposed components—you can extend the life of your system and avoid expensive spring repairs. Orbit offers a wide range of reliable parts and accessories designed with longevity in mind, from anti-siphon valves to gear-drive sprinklers. For more ways to protect your irrigation investment, explore Orbit's complete selection of winterization-friendly products and start next season with peace of mind.