When winter temperatures plummet, frozen pipes represent one of the most destructive and expensive hazards a homeowner can face. A small rupture in an underground or indoor pipe can release hundreds of gallons of water per hour, causing catastrophic structural damage, mold growth, and costly property loss.
Understanding why pipes freeze and taking proactive preventative steps before severe freezing weather hits—keeps your plumbing safe all winter long.
Why Pipes Burst During Cold Weather
Contrary to popular belief, it isn’t the expanding ice itself at the point of freezing that usually ruptures a pipe.
When water freezes inside a pipe, it expands by roughly 9%. As the ice blockage expands, it traps water between the ice plug and closed indoor faucets. This creates extreme hydraulic pressure downstream within the sealed line. Eventually, the pressure builds up until the pipe bursts at its weakest point—often far from the actual ice blockage.
High-Risk Areas in Your Home
Pipes located in unconditioned spaces or along exterior walls are at highest risk during a freeze:
- Pipes in unheated basements, crawlspaces, attics, and garages.
- Plumbing running through uninsulated exterior walls or under kitchen/bathroom cabinets.
- Outdoor hose bibs, spigots, and irrigation lines.
Pre-Winter Prevention Checklist
Complete these structural preparations in autumn before freezing temperatures arrive.
Drain Outdoor Hose Bibs: Disconnect Outdoor Lines.
Disconnect and drain all garden hoses. Turn off indoor shut-off valves for outdoor spigots, then open outdoor faucets to drain remaining water completely. Install insulated foam faucet covers over outdoor hose bibs.
Insulate Exposed Piping: Cover Exposed Lines.
Fit foam pipe insulation sleeves or self-regulating heat tape over exposed water pipes in basements, crawlspaces, attics, and garages. Pay special attention to elbows and fittings.
Seal Air Leaks Around Lines: Block Cold Air Infiltration.
Inspect exterior foundation walls where pipes enter the home. Use expanding spray foam or caulk to seal gaps around dryer vents, wiring penetrations, and plumbing lines.
Seal Crawlspace Vents: Maintain Heat Flow.
Close or cover crawlspace vents during winter to prevent freezing winds from sweeping directly across subfloor plumbing lines.
Action Plan During Extreme Freeze Snaps
When sub-zero cold snaps or severe polar vortex events hit your region:
- Let Faucets Drip Gently: Allow a trickle of cold water to drip continuously from faucets connected to exposed pipes. Moving water reduces static hydraulic pressure buildup, preventing bursts even if ice begins to form.
- Open Cabinet Doors: Keep kitchen and bathroom vanity doors open so warm indoor room air circulates freely around hidden cabinet plumbing.
- Maintain Thermostat Temperatures: Keep your home’s heat set to at least 55°F (13°C) day and night—never turn off the heat when traveling during winter.
- Keep Interior Doors Open: Leave interior doors open so heat distributes evenly to rooms containing exterior wall plumbing.
What to Do If a Pipe Freezes
If you turn on a faucet during winter and only get a few drops of water, a pipe may be frozen:
| Action Step | Correct Procedure |
|---|---|
| 1. Keep Faucet Open | Open the affected faucet tap so melting water and pressure can escape as the pipe thaws. |
| 2. Locate Main Shut-Off | Know the exact location of your main water shut-off valve so you can close it immediately if the pipe ruptures during thawing. |
| 3. Apply Gentle Heat | Use a hairdryer, portable space heater, or warm towels wrapped around the pipe. Never use an open flame, blowtorch, or propane heater. |
| 4. Call a Professional | If the frozen section is inaccessible or inside a wall, contact a licensed plumber right away. |