Every fall, the water left sitting in your sprinkler lines, valves and backflow preventer is a problem waiting for a cold night. When it freezes it expands, and that’s how fittings crack and heads split. A blowout clears that water out with compressed air before the first hard freeze, so the system starts up clean in spring.
When to blow out your sprinklers
The short answer for the Salt Lake valley: mid-October through early November, and on the early side if you live up on the bench, where it gets colder sooner.
That lines up with what the water agencies say. The Central Utah Water Conservancy District tells homeowners on the northern Wasatch Front to shut sprinklers off from mid-October through November, and the Utah Division of Water Resources’ weekly lawn watering guide recommends most of the state shut off irrigation in the fall. Salt Lake City’s average first freeze (32°F) falls around October 20, based on 1991 to 2020 data.
The lawn doesn’t need much water this late anyway. Utah State University Extension puts the northern Utah irrigation season at April through October.
Why not just shut the water off?
Turning off the supply stops new water from coming in, but it leaves water sitting in the pipes, valves and heads. The Central Utah Water Conservancy District recommends an air-compressor blowout for exactly that reason: trapped water freezes and cracks fittings. It also recommends draining the backflow preventer and disconnecting garden hoses.
What happens during a blowout
- We shut off the water to the sprinkler system.
- We connect an air compressor to the system.
- We run air through one zone at a time until only mist comes out of the heads.
- We leave the valves and backflow preventer set for winter.
Other fall jobs to do at the same time
Utah State University Extension’s fall lawn guidance pairs nicely with a blowout:
- Final mow: take the last cut down to about 1.5 to 2 inches.
- Fertilize after the last mowing: late October or early November, with a quick-release nitrogen fertilizer at about 1 pound of nitrogen per 1,000 square feet. It helps the lawn green up early next spring.
- Deal with the leaves: a light layer can be mowed in place, but a thick layer left under snow can smother the grass. See our guide to fall leaves.
- Water evergreens during a dry fall if the ground isn’t frozen, so they go into winter hydrated.
Book your blowout
We do sprinkler blowouts across Salt Lake City’s east side, Millcreek, Holladay, Murray, Cottonwood Heights and nearby. Request a blowout or text us at 801-835-6776. Spots fill up fast once the first cold snap is in the forecast.
Sources
- Utah water agencies outline end-of-season yard care (Central Utah Water Conservancy District, October 2025)
- Weekly Lawn Watering Guide (Utah Division of Water Resources)
- Salt Lake City’s average first freeze (Axios, using Climate Central 1991–2020 data)
- How do I take care of my lawn in Utah in the fall? (USU Extension)
- November yard and garden tips (USU)