Winterizing Outdoor Plumbing & Irrigation Systems

Why winterization matters

Outdoor plumbing lacks the interior heating that protects indoor pipes. Water freezing in an irrigation line or outdoor faucet expands with 2,000+ psi of force — enough to crack brass valves, split PVC pipe, and destroy sprinkler heads. The Insurance Information Institute reports that frozen pipe claims average $11,000 per incident. Winterizing your outdoor plumbing takes 1–3 hours and costs $0–$300 DIY or $100–$400 professionally — a fraction of repair costs.

Outdoor faucets (hose bibs)

• Disconnect all hoses — a connected hose traps water in the faucet body, guaranteeing a freeze-crack
• Close the interior shut-off valve — located inside the house on the pipe feeding the outdoor faucet
• Open the outdoor faucet — drain remaining water after shutting off interior valve
• Install an insulated faucet cover ($3–$10 each) — provides 2–3°F of freeze protection for mild climates
• Consider frost-proof sillcocks — if replacing old faucets ($150–$350 installed), these have a long valve stem that shuts off water inside the heated wall

Irrigation system blowout

Sprinkler systems hold water in underground pipes, valves, and heads even when turned off. The industry-standard winterization method is compressed-air blowout:

• Air compressor requirements — 50–80 CFM for residential systems. Most homeowner compressors (2–6 CFM) are insufficient.
• Process — Connect compressor to the mainline; blow out each zone for 1–2 minutes until no water exits heads. Never exceed 80 PSI for PVC or 50 PSI for polyethylene pipe.
• Professional blowout cost — $50–$150 for a standard residential system (4–8 zones). Many landscaping companies offer fall packages.
• DIY risk — Over-pressurizing cracks pipes and fittings. Under-blowing leaves water that freezes. If unsure, pay for professional service.

Pool plumbing winterization

• Lower water level 4–6 inches below the skimmer opening
• Drain all pump, filter, heater, and chlorinator lines completely
• Blow out return lines and plug with expansion plugs ($2–$5 each)
• Add pool antifreeze ($10–$15/gallon) to skimmer and remaining lines — use propylene glycol (non-toxic), never automotive ethylene glycol
• Professional pool winterization: $150–$400 depending on pool size and equipment

Outdoor kitchen & water features

• Outdoor sinks — shut off water, disconnect supply lines, drain P-traps, add RV antifreeze to traps
• Fountains & ponds — drain pumps and store indoors, or keep running if rated for freezing temperatures
• Hot tubs — if closing for winter: drain, blow out jets, add antifreeze to pumps. If keeping open: maintain heat above 80°F and run circulation pump during freezes

Timeline & scheduling

Task	When	DIY cost	Pro cost
Disconnect hoses & insulate bibs	Before first frost	$10–$30	$50–$100
Irrigation blowout	Before ground freezes (Oct–Nov)	$0 (if you own compressor)	$50–$150
Pool winterization	When water drops below 65°F	$50–$100 (supplies)	$150–$400
Outdoor kitchen shutoff	Before first freeze	$10–$20	$75–$150

When to call a professional

Hire a plumber if you can't locate interior shut-off valves or if your outdoor plumbing has backflow prevention devices (required in many jurisdictions) that need proper draining. Hire a landscaping company for irrigation blowouts if you don't own a large compressor. Call an emergency plumber immediately if a pipe has already frozen — attempting to thaw without proper technique risks a burst. Pool owners without experience should hire a pool service company for the first winterization to learn the process.