Outdoor Plumbing Winterization Checklist — Prevent Frozen Pipes and Damage

A connected hose traps water in the faucet body and the pipe behind it. Even frost-free hose bibs cannot drain properly with a hose attached. Water trapped in the faucet body expands when it freezes, cracking the valve body or the pipe inside the wall. The resulting leak often isn't visible until spring when you turn the faucet back on — by then, water has been running inside the wall for hours. Disconnect, drain, and store all hoses.

Most homes have dedicated shutoff valves for outdoor faucets inside the home, typically in the basement or crawlspace near where the pipe exits through the wall. Close each valve fully. If you can't find a dedicated shutoff, the outdoor faucet is fed directly from the main supply — consider having a plumber install individual shutoffs ($150–$250 each) for proper winter protection. Without a shutoff, you can't drain the line.

After closing the interior shutoff valve, open the outdoor faucet fully to drain any water trapped between the shutoff and the faucet. Leave the outdoor faucet in the open position all winter — this allows any residual water to expand without building pressure if temperatures drop. Some interior shutoff valves have a small bleeder cap on the downstream side — open this too to allow complete drainage.

Foam faucet covers ($3–$8 each) add an insulation layer over the faucet body. They're especially important for standard (non-frost-free) faucets and as extra protection for frost-free models. Slip the cover over the faucet and tighten the drawstring or toggle. Hard foam covers provide better insulation than fabric bags. Replace covers that are cracked or compressed from prior seasons — they lose insulating value.

Locate the dedicated shutoff valve for your irrigation system — it's usually near the water meter or where the irrigation line branches from the main supply. Close it fully. This prevents any water from entering the irrigation system during winter. If the shutoff valve is stuck or won't close, have it replaced before winterization — otherwise water continues feeding the system and winterization is ineffective.

Gravity drainage doesn't remove all water from irrigation lines — low spots and sprinkler heads retain water that freezes. Professional blowout uses an air compressor (80–100 PSI, 20+ CFM) to force all water out of every zone. The technician cycles through each zone until no water exits the sprinkler heads. Cost is $50–$100 for a standard residential system. Do NOT use a small shop compressor — insufficient volume leaves water behind and can damage PVC pipe with pressure spikes.

The backflow preventer (PVB, RPZ, or double check valve) is the most expensive component in the irrigation system ($200–$600 to replace) and the most vulnerable to freeze damage. Above-ground PVB and RPZ assemblies must be drained by opening test cocks and relieving internal pressure. In mild-freeze climates, an insulated cover ($30–$80) provides adequate protection. In hard-freeze areas, drain completely — don't rely on insulation alone.

Set your irrigation controller to 'off' or 'rain mode' — this preserves your programmed schedules while preventing the system from running. If the controller is outdoors in an unprotected location, consider bringing it indoors or covering it. Remove backup batteries if the controller will be in freezing temperatures. An irrigation controller that activates during a freeze sends water into drained lines and can damage the entire system.

Shut off the supply from inside the home, then open all outdoor kitchen faucets to drain the lines. If the outdoor kitchen has a hot water connection, drain both hot and cold supply lines. Leave faucets open. For long runs of supply pipe exposed to weather, use compressed air to blow out residual water — gravity alone won't clear horizontal or low sections.

The P-trap under outdoor sinks holds water that can freeze and crack the trap. Either remove the P-trap and drain it, or pour 1–2 cups of non-toxic RV antifreeze (propylene glycol, NOT automotive antifreeze) into the drain. The antifreeze displaces the water in the trap and won't freeze. This also applies to outdoor bar sinks, prep sinks, and any fixture with a drain trap.

These appliances have small-diameter supply lines that freeze quickly and crack easily. Close the supply, disconnect the line from the appliance, and drain both ends. Misting systems have extensive tubing runs that hold significant water — blow them out with compressed air. Store disconnected tubing coiled in a protected location to prevent UV degradation and animal damage.

Water in the skimmer, return lines, and suction lines must be removed for winterization. Lower the water level 4–6 inches below the skimmer mouth. This allows the lines to be drained or blown out without pulling water back in. Do not drain the pool completely — the water weight prevents the pool shell from lifting due to groundwater pressure (hydrostatic uplift).

Use a shop vacuum on blower mode or an air compressor (15–25 PSI for pool plumbing — lower pressure than irrigation) to force water from all lines. Start at the pump and blow through each suction and return line individually. Insert winterizing plugs (expansion plugs) into each skimmer, return fitting, and suction line opening after blowing. Don't skip any line — one forgotten return with standing water can crack in a single freeze event.

Remove all drain plugs from the pump housing, filter tank, heater, chlorinator/salt cell, and any booster pumps. Store drain plugs in the pump basket so they don't get lost. Leave drain openings open all winter. For DE and cartridge filters, remove and clean filter media before storing. The pump impeller housing is especially vulnerable — a cracked pump housing costs $200–$500 to replace.

Some pool plumbing runs have low spots or complex routing that prevents complete water removal by air. Add non-toxic pool/RV antifreeze (propylene glycol — NOT automotive ethylene glycol) to these lines as insurance. Pour 1 gallon into each skimmer and main drain line. The antifreeze settles to the lowest point and prevents ice formation even if residual water remains.

Do a complete lap around the property. Check every faucet, hose bib, irrigation head, outdoor kitchen fixture, pool equipment pad, and water feature. Verify: all faucets are open (for drainage), all covers are installed, all hoses are disconnected, all equipment is drained. It takes one missed faucet or one connected hose to cause a freeze failure.

After each hard freeze (below 28°F for 4+ hours), walk the property and check for split pipes, cracked faucets, displaced insulation, and ice buildup. Catching a crack before the thaw lets you shut off the supply before water flows through the break. Thaw-related flooding is the most common freeze damage scenario — the pipe cracks silently during the freeze and floods when temperatures rise.

Take photos of every shutoff valve location and note its purpose. Create a simple checklist specific to your property that you can follow each fall. This saves time in future years and ensures nothing is missed if someone else handles winterization. Include shutoff valve locations for: main outdoor supply, each hose bib, irrigation system, outdoor kitchen, pool equipment, and any water features.