Winterizing Your Sprinkler System Before the Freeze

Water trapped in irrigation pipes through a hard freeze expands by about 9% and splits whatever holds it — cracked PVC, a ruptured backflow preventer, broken zone valves. None of it shows up until spring start-up, and by then it is a four-figure repair. The fix is a one-afternoon job when you have the right supplies on hand before the first cold snap.

Two ways to clear the lines

A manual drain opens the system’s drain valves and lets gravity empty the pipes — simplest where the layout drains to a low point. A compressed-air blow-out pushes the water out with air and is the more reliable method on flat or back-pitched zones. Stay within Hunter’s published limits — 80 PSI max for PVC pipe, 50 PSI max for polyethylene — and blow out one zone at a time, letting the controller advance the valves.

What you’ll need (stocked here)

• Insulated backflow bags. The most freeze-sensitive component sits above grade — bag it after draining. A small 7 in pouch fits a hose-bib breaker; 24x24 and 34x24 bags cover residential and light-commercial PVB and RP assemblies. See freeze protection bags.
• Winter plugs (#6–#12). Cap exposed pipe ends during the manual-drain procedure; mixed-size sets cover most residential systems.
• Drain valves. Auto-drain valves for the manual-drain method, plus Hunter HCV drain check valves for retrofit or replacement.

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