Sprinklers keep your lawn looking great most of the year, but when autumn rolls along, take some time to empty and insulate them, so they’ll be every bit as reliable next spring. If you fail to winterize your sprinkler system properly, any water left in the lines can freeze, expand, and crack when the cold weather hits, potentially causing costly damage to a likely expensive system. To prevent your sprinkler’s pipes from freezing this winter, follow this guide about learning how to winterize sprinkler systems around your house.
Tools & Materials
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- Pliers (optional)
- Safety goggles
- Foam insulating tape
- Foam pipe covers
Having the right tools makes this job much smoother. I’ve found that a good pair of pliers can save your hands when dealing with stubborn valves, and safety goggles are a must when water might spray unexpectedly. Foam insulating tape and pipe covers are affordable at most hardware stores, and they’re key to protecting exposed components from freezing. Based on my experience, spending a little extra on high-quality insulation materials can make a big difference in durability, especially if you live in an area with harsh winters. For instance, I noticed that thicker foam covers tend to hold up better against repeated freeze-thaw cycles, which can save you from replacing them every year.
Project Overview
Working Time: It can take 3 to 5 minutes per zone, so calculate based on your system size.
Total Time: Plan on 1 to 2 hours to complete this task.
Skill Level: Intermediate
Estimated Cost: $53 to $121
This project isn’t too tough, but it does require some attention to detail. The time it takes depends on how many zones your sprinkler system has—mine has four, so I’m usually done in about an hour if I’m not rushing. The cost can vary depending on whether you DIY or hire a pro for the blow-out step. From what I’ve seen, buying foam insulation and maybe renting an air compressor keeps you at the lower end of that price range. If you’re curious about long-term savings, consider this: a properly winterized system can prevent repairs that might cost you upwards of $500, according to data from HomeAdvisor. That’s a pretty good incentive to spend a couple of hours on this now!
Before You Begin
The first thing to do when beginning a sprinkler system winterizing project is to assess the best way to release water from your particular system. There are two main ways to go about this: One is to drain water from the valves, and the second is to use an air compressor to blow water out of the irrigation pipes. If you are wondering when to winterize sprinkler systems, many sprinkler system manufacturers recommend that homeowners drain their systems when temperatures dip to 30 degrees Fahrenheit. You’ll also need to determine the type of drain valve your system utilizes, as this dictates whether draining is automatic or manual. Manual-draining sprinkler heads have check valves on them, and they require that you pull a few levers to get things moving. Once you know what type of system you have, you can accomplish almost all the necessary winterization on your own with the information below—though, of course, you should review the owner’s manual and keep it nearby for reference.
Figuring out your system type is crucial, and I learned this the hard way when I assumed mine was automatic and skipped a step—ended up with a cracked pipe that cost me a few hundred bucks to fix. If you’re unsure whether your valves are manual or automatic, check for a lever or a solenoid (that PVC cap with wires). Also, timing matters. Draining at 30°F, as manufacturers suggest, is a solid rule of thumb, but I’ve noticed that in areas with unpredictable weather, like where I live, starting a bit earlier—like mid-October—can save you from getting caught by an early freeze. A quick tip: take a photo of your system’s layout before you start. It’s a lifesaver when you’re trying to remember which valve is which!
STEP 1: Turn off the main water supply, and turn off the backflow preventer if your system has one.
First, turn off the main water supply to the house, which is often found near your water meter. If your sprinkler has manual drain valves, also shut off the valves on the backflow preventer. A backflow device, typically located near the water main from which the sprinkler water is drawn, prevents pressurized, potentially contaminated water from mixing with the potable water supply. If you’re not using potable water for irrigation, your system may not include a backflow device. If it does, turn it off via two valve shut-off handles on the separate pipes feeding into the device. Just turn these rectangular handles clockwise one-quarter to one-half turn; use pliers if the valves are too tight to turn by hand.
Shutting off the water supply sounds simple, but it’s easy to overlook the backflow preventer if you’re not used to dealing with it. I’ve found that marking the shut-off valves with bright tape helps me locate them quickly each year. Also, if your backflow device is above ground, it’s extra vulnerable to freezing, so double-check that it’s off. According to the EPA, backflow preventers are critical for keeping your drinking water safe, so treating them carefully during winterization is a must. If your valves are stiff, don’t force them—grab those pliers to avoid stripping the handle.
STEP 2: Drain any water remaining in the irrigation system.
Your next move depends on the type of drain valve you have. If your sprinkler system uses an automatic drain valve, this spring-loaded drain valve will open every time the system shuts off because there is little to no water pressure running through the lines to press and close the valves. But this draining won’t release water trapped inside the valves themselves. On each valve of the sprinkler system, locate the solenoid, which looks like a PVC cap with wires coming out of it, and loosen it by hand so air can flow inside the system. Once this is done, water should drain out from each zone of the system’s mainline. If your sprinkler system uses manual drain valves, locate the valve at the lowest point on your system’s mainline. Wear protective goggles for this, because the water can be under pressure and it’s possible to open valves before they depressurize. Next, turn off the sprinkler system’s mainline shut-off valve. Then, open one of the control valves on the system. You may be able to do this from a controller, otherwise it’s a manual valve. Doing this will depressurize the sprinkler system mainline. Finally, slowly open the manual drain valve and allow it to drain fully. Follow this procedure for each manual drain valve on your system’s mainline. When all the water has drained, close each manual drain valve.
This step can feel a bit tedious, but it’s where the real protection happens. For manual systems, I’ve learned to go slow when opening valves—rushing can lead to a face full of water (yep, been there). If you’ve got an automatic system, loosening the solenoid is key, but don’t remove it completely or you’ll have a mess to clean up in spring. A pro tip: if your system is older, check for sediment buildup in the valves, as it can trap water and increase freeze risk. The Irrigation Association notes that improper drainage is the leading cause of sprinkler system damage in winter, so take your time here to get it right.
STEP 3: Open all of the drain valves.
After emptying the mainline via automatic draining or manual draining, make certain that no water remains around the various valves that could expand when temperatures drop. Depending on your system, you may have a “boiler drain valve” or a “stop and waste valve,” which will turn off the local water supply and also allow for draining that pipe. Locate this valve’s drain cap and open the valve to drain the last of the water left between the irrigation system and the backflow device. If you plan to hire professionals to perform a blow-out, move on to Step 4. If you’re looking only to drain the pipes, you can proceed to Step 5.
Opening every last valve might seem like overkill, but even a tiny bit of water can cause trouble when it freezes. I once skipped a small drain valve because it was hidden behind some shrubs, and it led to a cracked fitting. If your system has a stop and waste valve, it’s usually buried a few feet underground, so you might need to dig a bit to access it. A quick heads-up: if you’re in an area with heavy clay soil, like parts of the Midwest, water can pool around these valves, so double-check they’re fully drained. This small step can save you from a repair bill that could easily hit $200 or more.
STEP 4: Blow out the irrigation pipes with an air compressor. (We recommend hiring a professional for this step.)
Assuming that your sprinklers are relatively new and installed correctly with the irrigation pipes sloping downward toward the valves (where water can release at the lowest point in the system), gravity will guide nearly all the water out after you’ve relieved the pressure in the mainline. But it’s hard to know for certain that there’s not some left behind—say, caught around a dip or curve in a pipe that has shifted since installation. For this reason, experts recommend calling in a professional to take a further precaution that will release any last lingering water remaining in the sprinkler system: blowing out the pipes using an air compressor. You might already own an air compressor and use it to power your nail guns and other air tools; perhaps it even boasts the capability to generate more than the recommended 50 pounds per square inch (psi) needed to clear a sprinkler system’s worth of flexible polyethylene pipes, or the 80 psi needed to blow out rigid PVC pipes. Still, experts advise against DIYing this step for a few reasons: Safety. All kinds of potential injuries can arise when using an air compressor, from valve tops blasting off to flying debris. The typical at-home air compressor might generate about the same force that a pro’s will, but it probably will not have the same volume as the professionals’ machine (most pros use a 10 cubic-feet-per-minute compressor). A professional-quality air compressor can blow out sprinklers quickly and thoroughly. Using homeowner-grade equipment can take significantly longer and may potentially leave water behind, which is not a risk we think is worth taking. Hiring a pro to blow out a sprinkler system just isn’t that expensive. Angi estimates the cost to blow out a sprinkler system at $100 to $250, which is a reasonable rate compared to having to replace or repair your system if your DIY goes wrong. In short, consider asking an expert to winterize your sprinkler system with an air compressor. After the professionals connect their air compressor to the hose leading from the water main supply and blow out your sprinkler system zone by zone, they should also close the main shut-off valves. They’ll also drain any water that collected around your backflow preventer (the device that isolates the system’s backflow and keeps it safe from damage).
I’ll be honest—I was tempted to try the blow-out myself with my old air compressor, but after reading about the risks, I decided to call a pro. It’s not just about the pressure; it’s the volume that matters, and most home compressors just don’t cut it. The pros I hired finished the job in about 20 minutes, and it cost me $150, which felt like a steal compared to the potential cost of replacing pipes. If you’re on the fence, consider that a single frozen pipe can lead to repairs costing $500 or more, per HomeAdvisor’s data. Plus, pros often spot small issues—like a leaky valve—that you might miss, saving you headaches down the road.
STEP 5: Insulate any system components that are located above ground.
If any parts of your sprinkler system—including pipes, backflow preventers, and main shut-off valves—are above ground, it’s a good idea to insulate the exposed parts. Local hardware stores usually offer foam insulation tape, foam pipe covers, and other winterizing protection. Following package instructions for the foam insulating products, cover exposed pipes and other system parts to protect against freezing or cracking, taking pains not to block valves or drainage ports.
Insulating is one of those steps that feels like a chore but pays off big time. I use foam tape because it’s easy to wrap around oddly shaped fittings, and I’ve noticed it holds up well even in windy, snowy conditions. One trick I picked up: cut the foam covers to fit snugly around curves and joints, and secure them with zip ties for extra staying power. According to the Department of Energy, proper insulation can reduce heat loss by up to 70%, which applies to preventing freeze damage in pipes. Just be sure to check that no drainage ports are covered, or you’ll trap moisture and defeat the whole purpose!
STEP 6: Consult your owner’s manual for recommendations that are specific to your system.
Some systems require that valves be stored indoors and pipes capped during the winter. Consult your owner’s manual to find out the recommendations for your particular sprinkler system.
Your owner’s manual is like the bible for your sprinkler system—don’t skip it. Mine had a specific note about removing certain valves and storing them in my garage, which I wouldn’t have known otherwise. If you’ve lost your manual (like I did once), check the manufacturer’s website; most have digital versions available. Also, some systems have unique quirks—like needing extra insulation for certain fittings—so taking a few minutes to read up can prevent costly oversights. I’ve found that jotting down a quick checklist from the manual keeps me from missing anything critical.
STEP 7: Program the system not to run during the winter season.
If your sprinkler system is on a timer, be sure to shut it off for the season. (Remember to reprogram it in the spring!) It’s also possible that you have a “rain mode,” which stops the sprinklers without turning off the timer when you get precipitation during the regular season. You can turn rain mode on for the winter to prevent the system from watering. This way you can avoid shutting the system off and losing the programmed settings on your sprinkler controller, which would leave you with the hassle of reprogramming come spring. The sensor uses such a small amount of energy that leaving it on through the winter won’t typically add much to your energy costs. In the spring, simply turn off the rain mode and watering will resume like clockwork.
I love the rain mode trick—it’s a game-changer for keeping your settings intact. Last year, I forgot to shut off my timer, and the system tried to run in January, which was a mess. Now I always switch to rain mode, and it’s so simple to flip it back on in spring. If your system doesn’t have rain mode, just unplug the controller to be safe. Also, if you’re worried about energy costs, I’ve checked my bills, and leaving the sensor on adds maybe a couple of bucks over the winter—totally worth it to avoid reprogramming.
Final Thoughts
A bit of effort expended on the front end might save days of work and untold expense if your sprinkler system breaks down when temperatures dip and winter winds blow. These steps can help you with the winterization of sprinkler systems efficiently and effectively, ensuring that your sprinkler system won’t be adversely affected by colder weather.
Winterizing your sprinklers is one of those tasks that feels like a hassle but gives you peace of mind all winter long. I’ve seen neighbors deal with busted pipes because they skipped this, and the repair costs were no joke—sometimes over $1,000 for larger systems. Taking an afternoon to follow these steps is a small price to pay. Plus, it’s kind of satisfying to know your lawn will be ready to thrive come spring without any nasty surprises.
FAQs
Q. How do you winterize a sprinkler system with a backflow preventer?
Before you begin to drain your sprinkler system, you have to shut off all water supply to the system. This includes shutting off the water supply at the backflow preventer as you prepare to drain the sprinkler system.
Q. How much does it cost to winterize a sprinkler system?
According to HomeAdvisor, it can cost between $53 and $121 to winterize a sprinkler system. Purchasing a few supplies at the home improvement store will likely put you at the lower end of this range, while hiring a pro will drive the cost to the higher end.
Q. How much PSI is needed to winterize a sprinkler system?
Winterizing a sprinkler system requires about 50 pounds per square inch (psi) to clear a sprinkler system constructed of flexible polyethylene pipes, and 80 psi is needed to blow out rigid PVC pipes.
These FAQs cover the basics, but here’s a quick tip: if you’re dealing with a backflow preventer, make sure it’s fully drained, as even a small amount of water can cause cracks. On costs, I’ve found that shopping around for insulation materials at big-box stores versus local shops can save you a few bucks. And for PSI, if you’re hiring a pro, ask them to confirm the pressure they’re using—it’s a good way to ensure they’re doing the job right.
