How to Winterize a Sprinkler System, Step by Step
Winter can be hard on an irrigation system. Water left inside sprinkler pipes can freeze, expand, and crack pipes, fittings, or valves. A little preparation before the first hard freeze can save you from a much bigger repair in spring. The air blowout method is the most common approach for clearing water from the lines. Some smaller systems can be drained by hand instead. The right method depends on how your system is set up and what equipment you have available.
The Air Blowout Method
The air blowout method uses compressed air to push water out of the sprinkler lines before freezing weather arrives. Before you start, shut off the irrigation system at its dedicated water shutoff valve. You'll also need to make sure your compressor and connection point are set up correctly so you can clear the lines without putting unnecessary stress on the system.
Set up the compressor
Connect the compressor hose to the blowout port near the backflow preventer. Don't force compressed air backward through the backflow device itself, since that can damage the equipment. Once the hose is connected and the water supply is off, you're ready to start clearing the individual sprinkler zones.
Blow out each zone
Run each zone separately, starting with the one farthest from the compressor and highest in elevation. Watch the sprinkler heads as the water changes from a steady stream to a fine mist or fog. That change tells you that most of the water has been pushed out of the line, so you can move on to the next zone. Keep each zone to about two minutes to limit heat buildup that can damage components. If you're also preparing an irrigation system that relies on solar power, off-grid solar winterization covers another seasonal maintenance task. Once you've worked through all the zones, the next thing to check is air pressure. The safe pressure range depends on whether your system uses PVC or polyethylene pipe.
Pressure Limits by Pipe Material
Air pressure matters just as much as the blowout process itself. The right pressure depends on the material used for your sprinkler pipes, so check the system before connecting the compressor. Using too much pressure can damage fittings or other sprinkler components.
Pipe Material | Maximum Air Pressure |
PVC | 50-80 PSI |
Polyethylene (PE) | 30-50 PSI |
For systems with mainlines under 2 inches in diameter, a compressor rated for at least 50 CFM is typically needed. It also needs enough airflow to keep water moving through the zone while the sprinkler heads are open. A high PSI rating alone isn't enough. The compressor needs enough CFM to keep pushing water through the lines as each zone runs.
You don't need to use the highest pressure possible. Use enough air to clear the water without putting unnecessary stress on the pipes, fittings, valves, or sprinkler heads. If your sprinkler system is far from a convenient outlet, EcoFlow's portable power stations can provide power for compatible equipment near the valve box or farther out in the yard.
Winterizing Without a Blowout
Not every sprinkler system needs an air compressor. Some smaller systems have manual drain valves that let you remove water from the pipes through gravity. Open the valves one at a time and let the water drain from the low points and ends of the piping. You'll still need to drain the backflow preventer separately. Open its test cocks to a 45-degree angle so trapped water can drain from the device. A manual drain can work well if your system has the right valves and you know where they're located. If you need a compressor or shop-vac for other parts of the job, having portable power nearby can also make outdoor winterizing easier.
If you need more battery capacity for longer jobs or want to keep more equipment running, the EcoFlow DELTA 3 Plus gives you more room to work with. Its capacity can expand from 1kWh to 5kWh, while the 1,800W output provides the same base AC output as the EcoFlow DELTA 3 Classic.
Whichever method you choose, there are a few common mistakes that can cause problems during winterization. A quick check before you finish can help make sure the lines, valves, and controller are ready for freezing weather.
Manual Drain Method for Systems Without a Compressor
Not every sprinkler system needs an air compressor for winterization. If your system has manual drain valves at the low points and ends of the piping, you can use gravity to remove water from the lines. Open the valves one at a time and let the water drain fully before moving to the next one. This method works best when the drain points are easy to access and the system is designed to release water this way.
The backflow preventer still needs to be drained separately. Open its test cocks to a 45-degree angle so trapped water can escape from the device. Don't assume that draining the sprinkler lines also empties the backflow preventer. If you're already preparing your house for freezing weather, winterizing your home covers other seasonal tasks you can tackle at the same time. Before you finish, check the drain points and backflow preventer again to make sure water isn't left trapped in the system.
Common Winterizing Mistakes to Avoid
Winterizing doesn't take much time once you know what to check. A few overlooked steps, though, can leave water in the system or put extra stress on its components during a freeze.
Forgetting the backflow preventer
Draining the sprinkler lines doesn't necessarily empty the backflow preventer. Water can stay trapped inside the device and freeze when temperatures drop. Drain it separately by opening the test cocks to a 45-degree angle, then check the device before finishing the job.
Using too much air pressure
More air pressure doesn't mean a better blowout. Using pressure that's too high for the pipe material can damage fittings or force sprinkler heads off their risers. Check whether your system uses PVC or polyethylene and stay within the recommended pressure range.
Running a zone for too long
Once the sprinkler heads are producing a fine mist or fog, most of the water has been pushed out. There's little reason to keep running compressed air through the zone after that point. Limit each zone to about two minutes to reduce heat buildup that can damage valves and seals.
Unplugging the controller
The irrigation controller needs attention after you've finished draining the system, too. Instead of unplugging it, leave it in "off" or "rain mode" so its programming stays intact. This also helps avoid some of the moisture and programming issues that can come from simply disconnecting the controller.
Conclusion
Winterizing a sprinkler system means getting the water out before freezing temperatures arrive. For systems that support a blowout, work through each zone one at a time and keep the air pressure within the range for the pipe material. PVC systems can use 50-80 PSI, while polyethylene systems use 30-50 PSI. A manual drain can work for some smaller systems with suitable drain valves. Whichever method you use, don't forget the backflow preventer. If you need to run a compressor or shop-vac away from a convenient outlet, the EcoFlow DELTA 3 Classic and EcoFlow DELTA 3 Plus can provide portable power for compatible equipment.
FAQs
Do I need an air compressor to winterize a sprinkler system?
Not always. Some smaller irrigation systems have manual drain valves at the low points and ends of the pipes, allowing water to leave through gravity. Systems without suitable manual drains may require the air blowout method.
What PSI should I use to blow out PVC sprinkler pipes?
For PVC sprinkler pipes, use 50-80 PSI when blowing out the system. Stay within that range instead of simply using the highest pressure your compressor can produce. Too much pressure can damage fittings or force sprinkler heads off their risers, so check the pipe material before starting.
How long should I blow out each sprinkler zone?
Blow out each zone for about two minutes at most. Watch the sprinkler heads as the water changes from a steady stream to a fine mist or fog. Once that happens, move to the next zone instead of continuing to run compressed air.
What happens if I don't winterize my sprinkler system?
Water left inside the pipes can freeze and expand when temperatures drop. That can crack pipes, fittings, valves, or other sprinkler components. You may then find leaks or other damage when you turn the system back on in spring.
For press requests or interview opportunities, reach out to our media team
media.na@ecoflow.com