Winterize your irrigation before the first hard freeze.

One burst backflow preventer can cost more than a decade of plow service. A twenty-minute blowout in October prevents it. If you run sprinklers in Hartford County, winterizing your irrigation system is the cheapest insurance you'll buy all year — and it's one of the few fall jobs where waiting a couple of weeks too long can wreck hundreds of dollars of brass and pipe. Here's the order of operations, and where to draw the line and call a pro.

Do it before the first hard freeze — and don't gamble on a warm fall

In Hartford County the first hard freeze typically lands somewhere from mid-to-late October into early November. "Hard freeze" means the ground and the shallow lines start locking up, not just a light frost on the grass. That's your deadline. We've seen plenty of warm falls tempt homeowners into pushing this into November, and most of the time they get away with it — until the one year an early cold snap drops in overnight and cracks a line while they're still thinking about it.

The math is simple. The job takes about twenty minutes for an average system. A cracked backflow preventer, split poly lines, or a broken valve costs you real money and a spring headache. Don't play the odds against the weather. Get it done while you're still raking leaves.

Why trapped water is the whole problem

Water expands roughly nine percent when it freezes. That doesn't sound like much until you remember it's happening inside a sealed brass body or a run of buried poly pipe that has nowhere to give. A single ounce of water left sitting in the low spot of a line, or trapped in the guts of a backflow preventer, turns into a wedge of ice that pushes outward with enough force to crack cast brass and split pipe walls.

The backflow preventer is the part that hurts. It sits above ground, it's full of small chambers and check valves that love to hold a little water, and it's the most exposed piece of the whole system. That's why it's the number one casualty every spring. The goal of winterizing isn't to get "most" of the water out — it's to get essentially all of it out of every zone and every valve, so there's nothing left to freeze.

The order of operations

Do these in sequence. Skipping around is how water gets left behind.

1. Shut off the water supply at the main valve. Find the isolation valve that feeds the irrigation system — usually near where the line taps off your main, or at the backflow assembly. Close it. This stops fresh water from refilling the lines while you drain.
2. Shut down the controller. Set the timer to "rain" mode or turn it off entirely so it doesn't try to run a cycle in the dead of winter and burn out a valve solenoid firing a dry line. If your controller has a battery backup for the clock, that's fine to leave in.
3. Drain the lines. There are three ways, depending on how your system was built: a manual drain (you open drain valves at the low points and let gravity do the work), an automatic drain (valves that open on their own once pressure drops below a set point), or the blow-out method (compressed air pushes the water out). Manual and auto drains alone often leave water sitting in flat runs and around the heads, which is why most systems in our climate get a blow-out to finish the job.
4. Blow out each zone — one at a time, low pressure. This is the step people rush and regret. Details below.
5. Insulate and protect the backflow preventer and any above-ground piping. Wrap the exposed brass and pipe with insulation and cover it. This protects whatever trace moisture remains and shields the assembly from the worst of the cold.

The blow-out method, done right

The blow-out is where you can save your system or destroy it, so slow down here. You'll connect an air compressor to the system downstream of the backflow — never blow air backward through the backflow preventer. Then you run the zones one at a time, letting the compressor push the water out through the sprinkler heads.

Keep the pressure low. For poly and PVC systems, stay around 50 psi — never crank it up thinking more pressure means a better clean-out. It doesn't. High pressure with no water in the line to cool things down melts fittings, blows seals, and cracks risers. Run one zone until you see the heads spitting mostly mist instead of water, then stop and move to the next. Don't hold air on a dry zone longer than it takes to clear it.

Wear eye protection, and never stand directly over a sprinkler head while a zone is charged — heads can pop up hard or shoot debris. Work one zone, catch your breath, move on. Patience beats horsepower every time on this job.

More air pressure never cleans a line better — it just finds the weakest fitting and destroys it. Low and slow, one zone at a time, is the whole trick.

A straight word on safety

Compressed air is genuinely dangerous. It's not the same as running water — a charged line stores real energy, heads can launch, and debris moves fast. Over-pressurizing doesn't give you a warning; it just breaks the weakest part of the system, sometimes violently. If you're not confident about the pressure, the connection point, or where your backflow and drains are, that's your signal to hand it off. There's no shame in it, and a pro blow-out costs a fraction of the repair. Call someone if the assembly is complex, if you can't locate the main shutoff, or if you've never done it before and don't have the right compressor.

The bottom line

Winterizing irrigation is a small job with an outsized payoff. Shut off the supply, kill the controller, drain the lines, blow out each zone one at a time at low pressure, then insulate the backflow. Do it before the first hard freeze — mid-to-late October into early November around here — and don't let a warm fall talk you out of it. If any part of it feels over your head, get it blown out professionally and sleep easy. Twenty minutes now beats a cracked backflow and a ruined spring startup later.