When to Winterize Your Sprinklers in Carson City (and What Actually Breaks First)
- Wickstrom Ace Hardware
- 3 days ago
- 6 min read
In Carson City, NOAA's records put a 1-in-10 chance of a 32°F night by September 24 and a 9-in-10 chance by October 20. That makes the back half of September the sensible window for this job, not October.
But the date on the calendar is the easy part. The part most people get wrong is what they are protecting. Almost every guide online frames this as one decision, blow out the lines or don't, and that framing sends people worrying about buried pipe while the thing that actually splits sits in plain sight on the side of the house.
Beat the first freeze — come see what we have.
Come see what we have for hose bib covers, backflow insulation and air compressors at 971 Topsy Ln. Tell us what your system has and we'll help you work out what fits.
Open Mon–Sat 8–7, Sun 9–6 · (775) 434-1030
Three freeze thresholds, three different problems
A freeze is not one event. Carson City gets three, and they arrive weeks apart. Using NOAA data for our area, the first occurrence of each runs roughly:
32°F, a light freeze. From September 24 at the early end to October 20 at the late end.
28°F, a moderate freeze. Early October into the first days of November.
24°F, a hard freeze. Mid-October into mid-November.
Here is why that matters. Buried lateral lines sit under a foot or more of soil, and soil holds heat. A single 32°F night does not reach them. What a 32°F night does reach is anything sitting in open air: the hose bib on your wall, the backflow preventer above the valve box, a hose you left connected.
So the honest sequence for a Carson City yard is that your above-ground fittings have a late-September deadline and your buried system has a late-October one. Those are different jobs with different urgency, and treating them as a single October chore is how people end up replacing a split hose bib in March.
Start with the hose bibs, because they fail first
A hose left connected over winter is the single most common cause of a burst outdoor faucet. Water sits trapped in the bib, freezes, expands, and splits the pipe behind the wall where you cannot see it. You often do not find out until spring, when you turn the water on and it comes out inside the crawlspace.
Disconnect every hose. Drain them and coil them somewhere out of the sun. Then fit an insulated cover over each bib. If you have frost-free sillcocks you still disconnect the hose, because a frost-free bib cannot drain with a hose attached, which defeats the entire mechanism it is named for.
This takes about ten minutes for most houses and it is the highest-value thing on this list.
Then the backflow preventer
Your backflow preventer is the brass assembly standing above ground near where the irrigation line leaves the house. It is exposed, it holds water, and it is the most expensive single component in a residential system.
Colorado State University Extension is direct about one point that a lot of DIY videos get wrong: never blow compressed air through a backflow preventer. The rubber seals inside can melt from the heat of the air. On a pressure vacuum breaker, the right move is to work the ball valves and test cocks back and forth a few times, then leave them half open so any water still inside has room to expand instead of cracking the body.
Insulate what remains. A cover, a wrap, an insulated bag, anything that keeps the assembly out of direct wind.
Now the buried lines, and which method you actually need
This is where the internet's binary framing falls apart. What you should do depends on what you have.
If your system has manual drain valves at the low points, open them, let the lines gravity-drain, and leave them open through winter. Then open the test cocks on the backflow to release any trapped pressure.
If your system has automatic drain valves, they release when line pressure drops below roughly ten psi, so shutting off the supply and running a zone briefly is usually enough to trigger them.
If you have neither, or you are not sure which you have, the blowout is the reliable route.
Worth knowing before you decide: CSU Extension's position is that drain valves in general are not fully dependable, because buried pipe shifts over the years and a low point that drained cleanly in 2019 may not be the low point any more. That is a fair caution, and it is more relevant here than in a mild-winter climate. We reach 24°F most years.
If you are doing the blowout yourself
Buy or borrow a compressor with enough sustained volume to actually clear a zone, and respect the pressure limits. CSU Extension gives 40 to 80 psi as the working range, with 80 psi the ceiling for rigid PVC and 50 psi for polyethylene pipe. Going higher does not clear the line faster. It cracks fittings.
Run each zone in two short cycles rather than one long one. A rotor spinning on dry air heats up, and heat is what damages the internals. Two short passes purge the line without cooking the heads.
Wear eye protection. Water and grit leaving a head under eighty psi goes further and faster than people expect.
We sell air compressors at the store, and if you tell whoever is at the counter what size system you are clearing, they can point you at one that will actually do the job rather than one that stalls halfway through a zone. A compressor sized for filling tires will not blow out an eight-zone yard.
The controller
Two options, and the choice barely matters.
Some controllers have a rain or off mode that keeps your programmed schedule in memory while suspending watering. Use it if you have it. Otherwise just cut power at the breaker or unplug the unit, and write your zone timings on a piece of tape stuck inside the cabinet door before you do. Spring you will be grateful. Spring you will not remember that zone four ran eleven minutes.
What this looks like as a sequence for working sprinklers
Late September: disconnect hoses, cover hose bibs, insulate the backflow preventer.
Early to mid October: shut off the irrigation supply, drain or blow out the lines, shut down the controller.
Any night the forecast dips below freezing before you have finished: at minimum, get the hoses off.
Common questions
When should I winterize sprinklers in Carson City?
Above-ground fittings by the last week of September. Buried lines by mid-October. NOAA puts our first 32°F night anywhere from September 24 to October 20, and the first 24°F night from mid-October onward.
Can I winterize a sprinkler system without a blowout?
Yes, if your system has working manual or automatic drain valves and you use them. Open the drains, release pressure at the backflow test cocks, and leave the drains open. The caveat is that buried pipe shifts over time, so a system that drained cleanly for years can develop a low point the valves no longer reach.
What pressure should I use to blow out sprinklers?
40 to 80 psi. Eighty is the maximum for rigid PVC and fifty for polyethylene, per Colorado State University Extension. Two short cycles per zone rather than one long one.
Do I need to do anything to the backflow preventer?
Yes, and do not blow air through it. Work the ball valves and test cocks, leave them half open, and insulate the assembly.
What does it cost?
If you are hiring it out, a blowout is a service call from a landscaper or irrigation contractor. If you are doing it yourself, the recurring cost is close to nothing once you own a compressor, and the hose bib covers are the cheapest insurance on this entire list.
Is a frost-free hose bib enough on its own?
Only with the hose disconnected. A frost-free bib drains itself through the wall when you shut it off, and a connected hose blocks that drain.
One last thing
If you only do one item on this page this month, disconnect the hoses. It costs ten minutes, it needs no tools, and it prevents the most expensive and most hidden failure in the whole list.
The rest can wait for the buried-line deadline in October. If you are already thinking about next spring, our guide to building raised beds for the high desert is the other half of this conversation.
Bring this list to the counter on Topsy Lane.
If you are not sure what your system has, describe it to us and we will work it out with you. Come see what we have for the three things most winterizing runs come down to:
Insulated hose bib covers — the cheapest insurance on this list.
Backflow insulation — keeps the most expensive component out of the wind.
An air compressor sized for your zone count, not for filling tires.
Wickstrom Ace Hardware · 971 Topsy Ln, Ste 334, Carson City, NV 89705 · (775) 434-1030 · Mon–Sat 8–7 · Sun 9–6
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