Provo City's building code puts the frost line at 30 inches.
A great many sprinkler lines in this valley are buried at 18 to 24 inches, which is entirely normal for irrigation and entirely shallower than the number above. That gap is why winterization is not a maintenance suggestion here the way it is in milder places. It is the difference between a system that works in April and a system that needs a plumber and a shovel.
Water expands about nine percent when it freezes. That is enough to split PVC, polyethylene, copper, brass valve bodies, filter housings and sprinkler heads without discrimination. It does not care what your pipe is made of.
The two dates that define the season
Everything about fall irrigation timing sits between two events.
Secondary water shutoff. Most Utah Valley cities and canal companies shut pressurized irrigation off around the middle of October and turn it back on around the middle of April. Your city publishes its own dates and they vary by a week or two.
First hard freeze. In Utah County, first frost typically lands somewhere in the second or third week of October. A frost is not the danger; a sustained hard freeze is. But frost is the warning shot, and the gap between the two can be short.
Which produces a simple rule: book for the first half of October. Late September is fine and increasingly popular. November is a gamble on the weather in a year when the weather has been unreliable, and it is also when every contractor in the valley is booked solid and nobody is discounting anything.
If you are on culinary water rather than secondary, you have more flexibility on when you stop watering — but exactly the same deadline on when you blow the lines out, because the pipe in the ground does not know where the water came from.
Draining versus blowing out
You will find people who insist a properly pitched system with working drain valves does not need a compressor.
They are technically correct and practically wrong. Gravity drainage assumes your laterals were installed with consistent fall toward the drains, that the drains still work after a decade underground, and that no low spot anywhere in the system holds a pocket of water. In a professionally engineered commercial install those assumptions might hold. In a residential system built in stages by three different people over twenty years, they do not.
The component that settles the argument is the backflow preventer. On a culinary-fed system it is a rigid metal assembly sitting above ground, exposed to air temperature directly, with no soil insulating it at all. It is the most expensive single part of a residential irrigation system to replace and it is the first thing to crack. Gravity does nothing for it.
What a good blowout looks like
The whole job is fifteen to twenty minutes on a typical yard. What separates a good one from a bad one is entirely in the details.
The sequence: shut off the water supply at the master valve. Connect a compressor at the blowout port. Run each zone in turn, watching the heads, until they are throwing air instead of mist. Shut down the controller for the season. Open the test ports on the backflow assembly and close its ball valves. Open drain valves.
The pressure question is the one worth asking. The correct approach is high air volume at moderate pressure. Volume is what pushes water out of a line; pressure is what stresses the line. A contractor working with an undersized compressor and compensating by cranking pressure up is how heads get destroyed and fittings crack — and the damage frequently does not announce itself until you charge the system in April.
The second failure mode is running a zone too long after it is clear. Sprinkler heads are lubricated by the water moving through them. Several minutes of dry air spinning the gears generates heat and wears them out. A good technician moves on as soon as the zone runs dry.
Ask about both. The answers take ten seconds and tell you a great deal.
If you have no blowout port
Some systems, particularly older ones and some secondary installs, have no convenient connection point for a compressor. A contractor who finds this will usually tell you the lines will be left open to drain naturally instead.
That is an honest answer rather than a brush-off, but it is a downgrade in protection and it is worth treating as a repair item rather than a permanent condition. Adding a blowout connection is a small job compared to replacing a split mainline, and it converts an annual gamble into an annual routine.
The autumn phone call that is not a repair
Every October, Utah Valley irrigation contractors field a wave of calls that all say the same thing: the controller is running and nothing is coming out.
Almost none of these are broken systems. The city turned the secondary water off.
This happens in reverse every April, when people conclude their system died over the winter because it produces nothing on the first warm Saturday — three weeks before the pressurized irrigation supply is switched back on. Our guide to how Provo's water actually works covers the two-supply arrangement in detail, and the lawn care guide covers what it means for a watering schedule.
Before you pay anyone a diagnostic fee in October or April, check your city's secondary water schedule. It is free and it resolves a large share of these calls.
Spring startup, and why it is not the reverse of a blowout
Turning a system back on badly is how you find out what the winter did — expensively.
Open the main valve slowly. A sudden surge of water into dry pipe is a hydraulic shock that breaks fittings that survived the freeze perfectly well. Then run each zone manually and stand there and watch it. Every zone, all the way through.
This is the moment to find the head that cracked, the nozzle that is throwing sideways, the zone that will not pressurize because a valve diaphragm failed. Finding those in April costs you a Saturday morning. Finding them in July, when a brown patch appears and the lawn is already stressed, costs you the lawn.
Reading a sprinkler repair quote
Irrigation repair is a trade where the same described problem can be a twenty-dollar part or a four-figure excavation, and the difference is not always obvious to a homeowner.
Broken or misaligned heads. The most common repair and the cheapest. A head that has been mown, driven over or simply worn out. Parts are inexpensive and available at any hardware store in the valley; this is genuinely a do-it-yourself job for anyone willing to dig a small hole.
Valve failures. A zone that will not turn on, or worse, will not turn off. Usually a diaphragm or solenoid, both replaceable without replacing the valve body. A zone that runs continuously is an emergency rather than an inconvenience, because on culinary water it is metered.
Wiring faults. A zone that is dead with a healthy valve. Diagnosis takes longer than the repair and the time is the cost. Underground splices corroded by moisture are the usual culprit.
Mainline leaks. The expensive one. Constant wet ground, a drop in pressure, or an unexplained jump in a culinary water bill. This involves finding the leak and then excavating to it, and the finding is often harder than the fixing.
Low pressure across the whole system. Frequently a clogged filter, particularly on secondary water, which is untreated and carries debris. Check the filter before accepting a diagnosis of anything more dramatic.
Who is allowed to do the work
There is a real licensing line here and it is not where most people assume.
Maintenance and repair of an existing system is one thing. Installing an irrigation system is landscape construction and falls under a specialty contractor classification issued by the state's Division of Professional Licensing. If the crew that has been maintaining your yard proposes to install a new system, run a new mainline or reconfigure zones, that is a different job under a different rule, and asking about licensing at that point is entirely reasonable.
This matters more than it sounds, because irrigation work touches the drinking water supply. On a culinary-fed system the backflow assembly is the only thing standing between untreated irrigation water and the water in your kitchen tap, and cross-connection is exactly the failure that device exists to prevent. It is not a component to have improvised on.
Utah's threshold for when a contractor license is required has been amended in recent years and the figures quoted in various places disagree with each other. Our handyman services guide covers that in detail, including the categories of work that require a licensed trade regardless of the dollar amount.
Culinary versus secondary, and why your system is built differently
This is the fork in the road that determines what hardware you own, and a surprising number of Utah Valley homeowners do not know which side of it they are on.
Culinary water is treated drinking water. If your irrigation is fed from it, the system is legally required to have a backflow prevention device, because irrigation water sitting in a lateral full of soil bacteria must never be able to travel backward into the drinking supply. That device is above ground, it is expensive, and it is the freeze-vulnerable component discussed above. The advantage is availability: culinary water runs all twelve months.
Secondary water, also called pressurized irrigation, is untreated water delivered from a lake, reservoir or canal through a separate municipal network. It is substantially cheaper, it is the reason lawns in this valley are as green as they are in a desert climate, and it is seasonal. A fully isolated secondary system does not need backflow prevention, because there is no drinking supply to protect. It does need filtration, because the water arrives with sediment, algae and the occasional small object in it.
The practical consequences run in both directions. Secondary systems have fewer freeze-critical above-ground parts but far more filter maintenance. Culinary systems can be run in a warm November but cost meaningfully more to run in July. And homes that have been converted from one to the other over the years sometimes have leftovers from both, which is how you end up with a backflow assembly on a system that no longer needs it — still freezing, still cracking, still costing money to replace.
The failure you will not see until April
Freeze damage is quiet. That is what makes it expensive.
A split in a buried lateral does not announce itself in December. There is no water in the line to leak. The crack sits there through the winter, and the first anyone knows about it is the moment the system is charged in spring and water starts going somewhere it should not — into the soil, under a driveway, or in the worst version, into a crawl space through a wall penetration.
This is the argument for the slow spring startup and the zone-by-zone walk, and it is also the argument against skipping a blowout in a mild-looking autumn. The cost of the blowout is known and small. The cost of the alternative is unknown, deferred by four months, and discovered at the exact moment you most want the system to work.
There is a related trap in a warm winter. A few valley winters in recent memory have been mild enough that a skipped blowout produced no damage at all, which teaches precisely the wrong lesson. One survived winter is not evidence that the practice is unnecessary; it is evidence that a hard freeze did not happen to arrive that year.
The maintenance nobody does that pays for itself
Two things, both free.
Run every zone once in June and watch it. Not the controller test cycle — stand outside and look. You are checking for heads throwing at the wrong angle, heads that have sunk below grass level, nozzles clogged with grit, and dry wedges between heads where coverage does not overlap. Twenty minutes in June is the cheapest lawn improvement available in this valley.
Clean the filter. If you are on secondary water you have one, and it fills with the same lake and canal sediment the system is designed to carry. A clogged filter presents exactly as low pressure, and low pressure gets misdiagnosed as something expensive with impressive regularity.
Neither of these requires a contractor, a part, or a tool. Both prevent the calls that do.
Hiring: what to establish on the phone
Winterization is a high-volume, low-margin service performed by everyone from established irrigation firms to lawn crews adding an autumn revenue line to teenagers with a borrowed compressor. The quality range is correspondingly wide, and the work is invisible once it is done, which is a bad combination.
Four questions sort it out quickly.
What size compressor do you run, and at what pressure? Covered above. The answer you want involves volume rather than pressure, delivered without hesitation.
What is included, and what is extra? Specifically: is shutting down the controller included, is opening the backflow test ports included, and if you find a problem, is telling me about it part of the visit or the beginning of a separate quote?
Are you insured? Irrigation work happens next to gas lines, buried electrical and other people's property. This is a fair question for any trade and an easy one for a legitimate operator to answer.
When exactly? Autumn scheduling in this valley slips, because the entire county wants the same three weeks. Get a date rather than a week, and get a call-ahead.
The short version
Book the blowout for early October. Ask what compressor they use and at what pressure. Check the secondary water schedule before you assume anything is broken, in October and again in April. Charge the system slowly in spring and stand outside and watch every zone run. And remember the number that started all of this: the code says 30 inches, and your laterals are probably not that deep.
Blowing out the lines is the chore that marks the start of the season here; the lights going up across the valley are the part people actually look forward to. Our Utah Valley Christmas lights map covers all fifteen.
Related Guides
- Lawn Mowing and Yard Care in Utah Valley
- Provo's Water System, Explained
- Waterwise Landscaping in Utah Valley
- Handyman Services in Utah Valley
- Plumbers in Provo
- Hardware Stores in Utah Valley
- Tree Removal in Utah Valley
- Winter Tires and Canyon Driving in Utah
- Secondary Water and Water Shares in Utah Valley
- House Painters in Utah Valley: Why Exterior Paint Fails Faster Here
Last updated August 2026. City secondary water shutoff dates and first-freeze timing vary year to year — confirm your city's current schedule before planning around either.
Frequently Asked Questions
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