Most Northwest Ohio systems should be blown out between mid October and early November, after irrigation season is done and before the ground freezes hard. Waiting risks water sitting in pipes, valves, and the backflow preventer when a freeze hits, which can crack fittings and leave you with repairs in spring.
Why do sprinkler systems need to be winterized in Ohio?
Irrigation pipes hold water even after the zones shut off. Water expands by roughly nine percent when it freezes, and pipes, fittings, and valve bodies can’t stretch to make room. Something gives, usually at a joint, a valve, or a fitting near the surface.
Ohio makes this worse than a place with one steady cold season. Our winters swing above and below freezing many times, so water in a low spot can freeze, thaw, and freeze again. Systems also have parts that sit above ground or close to it, like the backflow preventer, and those take the first hit when temperatures drop.
When is the right time to winterize an irrigation system in Northwest Ohio?
For Wauseon, Toledo, and the rest of Fulton, Wood, and Lucas counties, the practical window runs from mid October to early November. The goal is to finish after you no longer need to water but before a sustained hard freeze. Most cool-season lawns here are slowing down by then and get enough moisture from fall rain.
Why not do it in September?
A warm, dry stretch in late September can leave a lawn thirsty, especially a newly seeded one. If you blow out the system too early, you may end up watering by hand. Fall overseeding is a common reason to keep the system running a bit longer.
Why not wait for the first freeze warning?
Because a cold snap in the forecast tends to send many people looking for an appointment at the same time. Once a freeze is on the way, schedules can get busy, and you may find yourself with a hard freeze coming and no open slot. An early cold night doesn’t always crack anything, but it’s a gamble with parts that can be costly to replace. A safer approach is to schedule in early to mid October rather than react to the weather.
What does a professional blowout involve, step by step?
A typical blowout on a residential system goes like this:
- Shut off the water supply to the irrigation system at the main shutoff, usually in the basement or a utility area.
- Drain the backflow preventer and open its test cocks or shutoffs as the model requires, so it can’t hold water.
- Connect an air compressor to the blowout port on the mainline. Volume of air (CFM) matters more than pressure, and the pressure needs to stay within what the pipe type can take.
- Work through the zones one at a time, starting with the zone farthest from the compressor. Air pushes water out of the heads until they spit only mist.
- Run each zone in short cycles rather than one long blast, because running air through a zone too long can overheat and damage the heads.
- Leave valves and the controller ready for winter: drain any manual drain valves, set the controller to rain or off mode, and confirm the water is off.
How long it takes depends on the size and layout of the system, and a smaller residential system can go fairly quickly. Either way, the order and the pressure control are what separate a clean blowout from a damaging one.
What damage happens when water freezes in the lines, backflow preventer, and valves?
Here is what can show up in spring when water was left in a system:
- Backflow preventer: The brass or plastic body can crack, and because it sits above ground, it is the most exposed part. Replacement is a common spring repair.
- Valves: Valve bodies and diaphragms can split. You might see a zone that won’t shut off, or one that leaks at the valve box.
- Pipes and fittings: PVC can crack at joints or along the pipe. Polyethylene pipe handles freezing a little better but fittings can still fail.
- Sprinkler heads and risers: Bodies crack and pop-up mechanisms get damaged, especially in low spots where water collected.
The frustrating part is that you won’t know until the system is turned on in spring. A small crack under the lawn can leave a soggy patch, low pressure in a zone, or water bubbling up where it shouldn’t be.
Can you winterize a sprinkler system yourself, and what are the risks?
Some homeowners do, and it can work if you have the right equipment. The catch is the compressor. A small pancake compressor often doesn’t move enough air to clear a full system, and cranking the pressure to compensate is how people break heads and fittings. Safety matters too, because pressurized lines can throw debris, so eye protection is a must.
The other common mistakes are doing zones in the wrong order, leaving the backflow preventer full, and forgetting to shut off the water supply first. If your system has a lot of zones, low spots, or a long mainline, it’s usually worth having someone do it. If you’d like to talk it through, you can read about our irrigation services and ask what fits your property.
What should you do in spring when the system is turned back on?
Turn the water on slowly. A sudden rush of pressure into empty lines can damage parts, so open the supply valve gradually and close any drain valves first. Then walk each zone and check:
- Heads that don’t pop up, or that spray crooked or weakly
- Soggy spots or geysers that signal a crack in a pipe or fitting
- Zones that won’t turn off or won’t turn on
- Leaks around the backflow preventer and valve boxes
A few weeks into the season, watch your lawn for dry patches that line up with a zone. They often point to a clogged or misaligned head you missed. If you find damage and want a second opinion, or you’d like to talk through timing for next fall, you’re welcome to reach out to our team.
Frequently asked questions
How late in the year can you still blow out sprinklers in Ohio?
You can often still do it in November if the ground isn’t frozen solid and the system is accessible, but the risk goes up every week. Hard freezes can lock up valve boxes and make the blowout port hard to reach. If you’re past mid November, call as soon as possible rather than skipping it.
Do drip irrigation lines need winterizing too?
Yes. Drip tubing and the fittings, filters, and pressure regulators on a drip zone can hold water and freeze. Drain the lines, remove and store any filters or regulators that sit above ground, and blow out the zone at a lower pressure than you’d use for spray zones.
Should I shut off the water to the irrigation system myself first?
It’s a good idea if you know where the shutoff is, since it saves time and avoids confusion on the day. Just don’t count on draining the lines without air, because gravity alone leaves water in low spots. If you’re not sure which valve it is, ask before turning anything.
Can freezing crack a backflow preventer?
Yes, and it’s one of the most common freeze failures. The backflow preventer sits above ground and holds water in its body, so a hard freeze can split it. Draining it and opening its test cocks or shutoffs during winterization is key.
How do I know if my system froze over winter?
You usually find out when you start it up in spring. Look for geysers, soggy spots, zones with weak pressure, valves that won’t close, or water leaking from the backflow preventer. Shut the system off if you see any of these and have it checked before running it again.