The first hard freeze is not the time to start thinking about your sprinkler system. In the Chicago suburbs, irrigation lines can crack when water is left sitting in pipes, while exposed backflow preventers and outdoor plumbing are especially vulnerable.
A proper winterization involves more than simply shutting off the water. The system needs to be drained and blown out correctly, with special attention given to the backflow preventer and each irrigation zone.
The best time to schedule your blowout is before the seasonal rush. Waiting until the first freeze can mean limited availability and costly repairs.
Every fall, the same call comes in: "I meant to get the sprinklers blown out, but I figured I had another week." Then a hard freeze rolls through on a Tuesday night, and by Wednesday morning there's a cracked backflow preventer or a split section of PVC out by the curb.
Here's what actually matters. The timing, who to call, and why frozen pipes cost so much more than the fix itself.
When to Schedule the Blowout
In the Chicago suburbs, the frost line typically reaches 12–18 inches by late November and can dig past 36 inches in a hard winter. Most irrigation lines are buried shallower than that, which means they don't need a deep freeze to crack, they just need one hard overnight freeze with water still sitting in the pipe.
The general rule for DuPage County: book your blowout for mid-to-late October, and have it done before the first sustained hard freeze, which typically shows up in early-to-mid November. Don't wait for a frost warning to call, by then, every irrigation contractor in the western suburbs has the same idea, and their schedule fills in days, not weeks.
A few signs your system should already be on the calendar:
Overnight lows have started dipping into the 30s.
You've already had your first frost advisory of the season.
Your landscaper or lawn service has stopped mowing weekly.
If any of those are true, you're not early anymore, you're on time, at best.
What a Real Blowout Actually Involves
A proper winterization isn't just shutting off the water at the valve. A qualified pro will:
Shut off the water supply to the irrigation system at the main valve.
Open the drain valves (if your system has manual drains) or prepare to force air through the lines.
Connect a compressor to the system and blow compressed air through each zone, one at a time, until water stops spraying from the heads.
Insulate or drain the backflow preventer — this is the part that cracks most often, since it usually sits above ground and fully exposed.
Set the controller to "rain mode" or power it down for the season.
That third step is where a lot of DIY attempts go wrong. Too little air pressure and water gets left behind in low spots of the line. Too much pressure, applied too fast, can damage valve diaphragms or blow out fittings that were never rated for it. This is a job where "close enough" isn't actually close enough.
Finding a Pro Worth Hiring
Look for a contractor who specializes in irrigation winterization specifically, not just someone with an air compressor in their truck. A few questions worth asking before you book:
What size compressor do you use, and how many CFM does it put out? Most residential systems need 80–100 CFM to clear the lines properly. Anything significantly under that and you're paying for an incomplete job.
Do you check the backflow preventer separately? This should be its own step, not an afterthought.
What's your cancellation and reschedule policy if the weather shifts? A pro who's flexible about squeezing you in before a cold snap is worth more than one who quotes the lowest price.
Local plumbing and landscaping companies across DuPage County typically charge somewhere in the range of $75–$150 for a standard residential blowout, depending on the number of zones. That's a small number to keep in your head next to what comes next.
What Frozen Pipes Actually Cost
This is the part homeowners underestimate every single year. A cracked irrigation line by itself might cost a few hundred dollars to repair come spring. But when freeze damage reaches your home's actual plumbing — a hose bib that wasn't shut off, a supply line in an uninsulated crawlspace, a backflow device tied into your main water line — the numbers change fast.
Nationally, insurance data shows the average payout on a frozen pipe and water damage claim now tops $30,000, and Illinois consistently ranks among the five costliest states for these claims. The pipe itself is rarely the expensive part, a straightforward burst-pipe repair often runs somewhere between $200 and $3,000. What runs the bill up is everything the water touches on its way out: drywall, subfloor, insulation, and the mold remediation that follows if it isn't caught fast.
The math isn't subtle. A $100 irrigation blowout and a few dollars of foam insulation on exposed hose bibs is cheap insurance against a five-figure claim you'll spend months untangling with your insurance company, assuming they don't argue it was a maintenance issue and push back on the claim entirely.
Get the blowout on the calendar this month. Don't make the first hard freeze the thing that reminds you.
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Share This Article: Sprinkler blowouts and winterization appointments don’t schedule themselves. But when was the last time anyone checked whether water was still sitting in the irrigation lines, or noticed an exposed backflow preventer and decided it could wait? Send this to a homeowner who needs the reminder before the first hard freeze hits.
