MaintainlyHow often should you winterize your sprinkler system?
Sprinkler / irrigation winterization once a year. The commonly recommended range is annually (fall). Water left in irrigation lines freezes, cracks pipes and heads. It is seasonal work, best done in autumn / fall.
An irrigation system is a network of buried pipes, valves and sprinkler heads, and draining alone can leave water behind. Hunter, one of the main irrigation manufacturers, warns that the remaining water can freeze, expand and crack rigid PVC pipe or rupture flexible polyethylene pipe. Compressed air is used to force that water out before the first freeze.
Why does winterizing your sprinkler system matter?
Water left in irrigation lines freezes, cracks pipes and heads.
What happens if you skip winterizing your sprinkler system?
Cracked pipe, damaged valves and broken sprinkler heads, all buried and mostly discovered in spring when the system is turned on and water appears where it should not. Hunter notes that water freezing in the backflow assembly damages its internal components and can crack the brass body.
What does the professional actually do?
- Shuts off the irrigation water supply
- Connects a compressor to the mainline after the backflow device, so that air is not blown through the backflow device itself
- Blows out each zone in turn, starting with the one furthest from the compressor, until no more than a fine mist comes from the heads
- Keeps air pressure within the manufacturer limit: Rain Bird says it must not exceed 50 PSI, and Hunter says never more than 80 PSI on PVC pipe or 50 PSI on polyethylene pipe, and always below the rating of the weakest component on the zone
- Works in short cycles of about two minutes per zone and stops once the zone is dry, because compressed air moving through dry pipe creates heat that can damage it
- Drains the backflow device separately and leaves its valves part open and its test cocks open for winter
- Switches the controller to off for the season
How do you choose someone qualified?
The important detail is that a blowout needs high air volume at low pressure, not high pressure. Rain Bird warns that some small shop compressors may not be adequate, and that letting a small compressor build up pressure and then releasing it in a surge is a dangerous practice that puts severe stress on every component. Ask what pressure the contractor regulates to and whether they blow through the backflow device (they should not).
What does it take?
How do you know winterizing your sprinkler system is overdue?
- The first freeze approaching, which is the trigger that matters
- Heads that did not pop up properly during the season, which should be noted for spring repair
- Wet patches in the lawn indicating a leak to be fixed before shutdown
What changes how often you need to do it?
- Zone count drives cost and time
- Polyethylene pipe has a lower air pressure limit than PVC
- Systems with a backflow device above ground need particular care
- Book ahead: the work has to be done before the first freeze
When should you stop and call someone?
Hunter recommends that a qualified licensed contractor does a blowout. Both Hunter and Rain Bird warn that compressed air can cause serious injury, including eye injury from flying debris, and say to wear eye protection and never stand over pipes, valves or sprinklers while the system is under air. A small compressor either fails to clear the lines or tempts you to raise the pressure, which is what damages the system. If your system has manual or automatic drain valves it may be designed to drain without air: check the installer paperwork.
Does this differ in the US, UK, Australia or Canada?
United States
Standard practice where the frost level reaches below the depth of the pipes. Backflow testing is a separate requirement set by the local water utility or city. San Antonio, for example, requires the backflow assembly on a lawn irrigation system to be tested every year by a licensed backflow prevention assembly tester. Check what your own utility requires.
United Kingdom
Domestic in-ground irrigation systems are uncommon. Where one exists, follow the installer or manufacturer instructions for draining it down and protect any above-ground components from frost. Outside taps and any above-ground pipework are the more usual freeze risk.
Australia
Freeze protection is irrelevant across almost all of Australia, so the blowout as such does not apply. The Australian seasonal irrigation task is the opposite one: checking and tuning the system before summer, replacing broken heads, and confirming the controller matches the watering days and hours permitted where you live. Rules are set locally. In Western Australia, Water Corporation enforces a mandatory winter sprinkler switch-off from 1 June to 31 August across Perth, Mandurah and parts of the South West and Great Southern, for scheme and bore water alike, with a $100 fine for using sprinklers during that period.
Canada
Needed wherever there is an in-ground system and the ground freezes, which is most of the country. The window between the end of the growing season and the first hard freeze is short, so book early. Backflow rules are municipal. Calgary, for example, requires the cross connection device on an in-ground irrigation system to be tested by a certified tester registered with the City when the system is turned on at the start of each irrigation season.
Frequently asked questions
Why does winterizing your sprinkler system matter?
Water left in irrigation lines freezes, cracks pipes and heads.
What happens if you skip winterizing your sprinkler system?
Cracked pipe, damaged valves and broken sprinkler heads, all buried and mostly discovered in spring when the system is turned on and water appears where it should not. Hunter notes that water freezing in the backflow assembly damages its internal components and can crack the brass body.
Does winterizing your sprinkler system differ by country?
Common US/CA. Less common UK. Blow out lines before freeze. AU: freezing is rarely the issue, so the seasonal job is checking the system before summer and matching your state's watering restrictions.
When in the year is winterizing your sprinkler system best done?
This is seasonal work. Plan it for autumn / fall, before the weather it protects against arrives.
How we put this together
The figures, intervals and legal points on this page were checked against the sources listed below. The default interval and accepted range are the ones Maintainly uses in its task library. Costs and times are typical ranges and vary by region and by home. Your own manufacturer's instructions come first, and gas, electrical and structural work belongs with a qualified professional. How we research and write.
Sources
- Winterizing Your Irrigation System, Hunter Industries. Checked 11 October 2026.
- Homeowner's Guide to Winterization, Rain Bird. Checked 11 October 2026.
- Annual Testing of Backflow Prevention Assemblies, San Antonio Water System. Checked 11 October 2026.
- Cross Connection Control Program, City of Calgary. Checked 11 October 2026.
- Sprinkler Switch-off, Water Corporation (Western Australia). Checked 11 October 2026.
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