Winterize Your Irrigation — In Oregon? Really?

The geyser nobody saw coming

You screw a hose onto the outdoor faucet on a mild spring day, turn it on — and water comes pouring out of the wall behind it. Not the faucet. The wall.

And if you’ve got sprinklers, multiply it. You flip the system on for the first time and instead of a gentle arc, a valve geysers, a zone won’t hold pressure, and the brass assembly up by the house is cracked clean through.

Here’s the part that catches people. None of that broke in spring. It all broke back in December, on one cold night nobody thought twice about. You’re just finding out now.

”Winterize? In the Willamette Valley? Really?”

Yes. Really.

We’re not Minnesota, and that mild reputation is exactly what gets people caught. The valley gets hard freezes most winters — typically starting in November, and in the low-lying spots around Aurora, Canby, and Hubbard, cold air pools and it can come earlier. A mild average is no protection. The valley only has to freeze hard once.

And the reason a freeze breaks things is worth knowing. Water is one of the few things on Earth that gets bigger when it freezes — about 9% bigger. Almost everything else shrinks in the cold. Water pushes outward, hard enough to split rock in nature and more than enough to crack brass, PVC, or poly pipe from the inside.

It’s not the cold that breaks the pipe. It’s water that had nowhere to go.

The trap on every house — hose or no hose

You don’t need a single sprinkler head to get burned this winter. Every home has at least one outdoor faucet, and it’s one of the most freeze-vulnerable spots on the place — sitting outside, exposed, above ground.

The classic mistake is leaving a garden hose screwed onto it over winter. The hose holds water against the faucet and blocks it from draining, so water sits in the bib, freezes, and cracks the pipe — often on the inside of the wall, where you can’t see it. It looks fine all winter. Then it thaws and floods the day you turn it on.

So here’s the job worth doing before the cold hits:

• Unscrew every garden hose, drain it, coil it in the garage.
• Drain your hose bibs. If there’s an indoor shutoff for the outdoor faucet, close it, then open the outside faucet to drain the line — and leave it open through the winter so any leftover water has somewhere to go.
• Cover exposed bibs with an inexpensive foam faucet cover.
• Don’t forget the tap on the unheated shed, barn, or detached garage — nobody’s out there to remember it.
• And find your main water shutoff now. If a line ever does let go, 2 a.m. is a bad time to be hunting for the valve.

That’s real freeze prevention, and it costs nothing but a minute of your Saturday.

If you have sprinklers, the same trap — everywhere at once

Add an irrigation system and the same thing happens, just spread across dozens of parts — valves, the manifold, poly and PVC lines, and sprinkler heads. Buried mainlines get some protection from a blanket of soil; the shallow and exposed parts don’t.

One part deserves special mention: the backflow preventer, the assembly that keeps sprinkler water from flowing back into your drinking water. Here in Oregon most of these sit below grade, tucked into an insulated box or vault; some are mounted above grade on the side of the house. The above-grade ones are the most exposed of all — but even the below-grade ones sit shallow, holding water in little brass chambers. Below grade is not the same as freeze-proof. Either way, that water has to be cleared before a hard freeze.

Winterizing is really two steps: shut off the supply, then get the standing water out. Shutting off alone does nothing — same failure as the hose bib, just with more places for water to hide. There are three ways to clear it: manual drain valves, automatic drain valves, or the professional blow-out, where safe, limited compressed air pushes water out of every zone.

Draining is genuinely worth doing, and it’s squarely a homeowner job. But gravity only clears what can run downhill. Water trapped in low spots, in flat or uphill runs, and inside sprinkler heads just sits there — and a foam cover slows heat loss but does nothing about water already inside a valve or assembly. Clearing that last water is what the compressed-air blow-out is for, along with draining the backflow by hand.

Here’s the honest warning, though: the compressed-air blow-out is not a do-it-yourself job, and we don’t recommend it as one. Too much pressure — and a shop compressor run wide open is far too much — blows out seals and shatters the very heads and valves you’re trying to protect. Done wrong, a cheap rental can leave you owning a badly damaged system and a repair bill far bigger than winterizing would ever have cost. This is the part to hand off: the right equipment, set to the right limited pressure, is most of the job.

Winterizing won’t make freeze damage impossible in a long, extreme cold snap — nothing does. But it clears the trapped water behind the overwhelming majority of freeze failures, which makes it the single best thing you can do.

What you get back

• No geyser, no cracked backflow, no zone that won’t pressurize.
• No water stain creeping across a wall from a burst you never saw.
• Money kept in your pocket instead of spent on an avoidable repair.

You flip the system on in April, it hums to life, and you never think about December again. That boring spring startup is the whole point.

It’s not free and it’s not a bargain — it’s a sensible once-a-year investment that heads off a much larger, unplanned one. The kind of insurance that pays for itself the first freeze it prevents. This is the fall half of a year-round rhythm; the summer companion piece is the other end of the calendar.

When to call us

Winterizing is part of the irrigation work we do — installs, repairs, smart upgrades, and seasonal blow-outs. The blow-out is where the right tools and the right pressure earn their keep, and it’s the part we’re glad to take off your hands. Get it on the calendar before the first hard freeze — not the week the first cold snap is in the forecast, because by then the schedule is full and the risk is already live.

We service irrigation across the north Willamette Valley — Woodburn to Lake Oswego, Newberg to Oregon City. When you’re ready, schedule a winterization or call (503) 678-7744 — the on-site estimate is free.