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A Gardening Know How report says turning off an irrigation system may leave water in pipes, valves and sprinkler heads, where freezing can cause damage. It recommends winterizing before the first hard freeze and says homeowners should use caution with compressed-air blowouts or hire a professional when the system or equipment is unsuitable.
A Gardening Know How report says homeowners should do more than shut off an in-ground sprinkler system before winter: water left in pipes, valves and sprinkler heads can freeze and damage components. The report advises winterizing before the area’s first hard freeze, while warning that compressed-air blowouts can also cause damage or injury if performed improperly.
Closing the water supply stops new water from entering the system, but it does not necessarily empty water already in buried pipes or components. The report says low points in pipes, valves and backflow preventers can retain water. As it freezes, water expands by about one-eleventh, potentially cracking plastic pipes, fittings, valves and sprinkler cases.
Drain valves may remove some water, but they rely on the lines draining as intended. The report says ground movement over time can leave buried pipe sections with low spots where water collects. It also notes that electric valves may retain water above an internal diaphragm, which may require compressed air to clear.
The report recommends closing the water supply, draining accessible low points and following the system’s instructions. For a blowout, it describes connecting a compressor to the system’s blowout port downstream of the backflow preventer, opening one irrigation zone, and increasing airflow gradually until the heads release mostly air and a fine mist. It says to turn the compressor off before changing zones and to avoid continuing once a zone is clear.
Preventing Freeze Damage Safely
Winterizing matters because a repair may be needed when irrigation is turned back on in spring if water has frozen inside vulnerable components. The report identifies cracked valves, split fittings and damaged pipes as possible consequences of leaving water behind. Such damage can affect system operation and require replacement or repair, though the report does not provide cost estimates.
Compressed air is not risk-free. The report warns that excessive pressure can dislodge nozzles or damage pipes and fittings, while water, grit or debris may be propelled from a head or open fitting. It advises wearing safety glasses, keeping clear of pressurized equipment and not forcing air against a closed valve. Homeowners who cannot safely manage the equipment or system may need a professional.
irrigation system winterization kit
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Timing Depends on Local Conditions
The report says to plan the work before the first hard freeze; in colder regions, that may mean early to mid-fall. It says an established lawn can generally be shut off somewhat early and green up again when watering resumes in spring. The specific timing depends on local weather and the system’s design.
Not every system requires the same procedure. The report says some areas with mild winters have systems without a blowout port, where shutting off the supply, turning off the controller and draining exposed components may be sufficient. Backflow preventers and exposed pipe are particularly vulnerable to cold air, while buried lines face greater risk when prolonged cold drives frost into the ground. These recommendations are general guidance, not a substitute for local conditions or the manufacturer’s instructions.
““That valve keeps new water out, but the water in the pipes, valves, and heads stays put.””
— Gardening Know How report
System Needs Vary by Location
The report does not establish one procedure or pressure setting for every irrigation system. Requirements depend on system layout, climate, available drain points and manufacturer guidance. Its example of about 5 CFM for one zone at a time is presented as suitable for many residential systems, not as a universal specification. The source material also does not provide a precise safe pressure limit for all equipment.
It is not clear from the report whether a particular homeowner’s lines can drain adequately without a blowout, or whether their compressor and fittings are compatible with the system. If the system lacks a blowout port, has unusual plumbing, or the owner is unsure how to isolate the backflow preventer, the report’s general steps may not apply. Local freeze forecasts and professional advice can help resolve those questions.
Prepare Before Temperatures Drop
Homeowners should check the forecast and their irrigation-system instructions, then shut off and drain the system or arrange a professional winterization before a hard freeze. Those choosing a blowout should use a compatible adapter, wear eye protection, open only the zone being cleared, and stop once water has been expelled rather than running air through dry lines.
After the blowout, the report says to leave the backflow preventer’s ball valves and test cocks half-open to reduce the chance of trapped water causing winter damage. Owners should confirm the correct position for their own equipment with its instructions. The next practical check comes in spring, when the system can be inspected for leaks or cracked parts before regular watering resumes.
Key Questions
Is turning off the sprinkler water enough?
Not necessarily. Water may remain in pipes, valves, low points and sprinkler heads after the supply is shut off. The report says those areas may need to be drained or cleared to reduce freeze-damage risk.
When should I winterize my sprinkler system?
Complete the work before the first hard freeze in your area. The report says colder regions often need to address it in early to mid-fall, but timing varies with local weather.
Can I use any air compressor for a sprinkler blowout?
No single compressor specification is suitable for every system. The report says airflow matters as well as pressure and cites about 5 CFM for many residential systems when clearing one zone at a time. Check the system’s requirements and avoid exceeding equipment limits.
Is blowing out sprinkler lines safe to do myself?
It can involve risks. The report warns that compressed air can eject water or debris and that excessive pressure may damage components. Wear safety glasses, keep clear of pressurized heads and fittings, and consult a professional if you are unsure about the procedure.
Do all sprinkler systems need a blowout?
No. The report says some systems in mild-winter regions may be designed to drain exposed parts without a blowout. The right method depends on local climate and system design; check the manufacturer’s instructions or ask an irrigation professional.
Source: rss
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