Protect your plumbing when the heat goes out: faucet drips, open cabinets, insulation, when to drain the system and what to do if a pipe freezes.
- Open cabinets and keep a thin drip running on exposed lines early in the outage.
- If the house nears freezing for long, shut off the main and drain the system.
- Never use flames or fuel burning devices to thaw pipes.
A winter outage can turn into an expensive plumbing problem. When the furnace is off, indoor temperatures drop, and water in pipes along cold exterior walls, in crawl spaces, garages and attics can freeze. Ice expands, and a pipe that freezes can split. You usually find out only after it thaws and water starts flowing.
This guide covers simple steps to take early, what to do if the outage drags on, and how to handle a pipe that has already frozen. Follow the advice of your local utility, municipality or a licensed plumber where it differs.
Start early, before the house gets cold
Pipes do not freeze the moment the heat stops. A well insulated home can hold warmth for many hours, so use that time well.
- Open the cabinet doors under kitchen and bathroom sinks, especially on exterior walls, so room air reaches the pipes.
- Let cold water drip from faucets served by exposed pipes. Moving water is harder to freeze. A thin steady drip is enough.
- Close garage doors and block drafts near basement windows and crawl space vents.
- Keep interior doors open to share the remaining warmth, unless you are confining your heat to one room (see below).
- Know where your main water shut off valve is, and make sure everyone in the home can find it.
If you are heating just one room
Many families confine themselves to a single warm room, as in our guide to heating a room without electricity. That helps people, but pipes elsewhere stay exposed. Think about which plumbing runs through unheated spaces. Bathrooms and kitchens on exterior walls are the usual weak points, as are laundry hookups and outdoor taps.
Insulation helps. Foam pipe sleeves, towels or blankets wrapped around exposed pipes slow heat loss. This will not stop freezing during a long cold snap, but it buys time.
When to shut off and drain
If the house is getting close to freezing and you expect the outage to last, the safest option is often to shut off the water at the main valve and drain the system. A typical sequence looks like this, but check your own home setup and your plumber's advice:
- Turn off the main water supply.
- Open the lowest tap in the house and the highest tap, plus other taps, to let water drain out.
- Flush toilets once to empty the tanks and bowls, then do not use them for water.
- Do not run hot water taps if the water heater is off. If you have a water heater, follow the maker's instructions for turning it off and draining safely.
- Leave taps open so any remaining water has room to expand.
Homes on a well or with hydronic heating, sprinkler systems or other special plumbing have extra steps, so ask a professional. Our well pump and well water guide covers the well side. Once you drain the system, you will need stored water for drinking and sanitation, so see how much water to store.
If a pipe has frozen
If a tap only trickles or gives nothing, a pipe may be frozen. Open the tap so water can flow as the ice melts, and find the likely section. If you can reach it, gently warm it with a hair dryer on a low setting (once power is back or from a safe power source), warm towels or a heating pad. Start nearest the tap and work back along the pipe. Do not leave a warming device unattended.
If you see a crack, bulge or leaking water, shut off the main valve immediately and call a licensed plumber. If you cannot find or reach the frozen section, or it is inside a wall, call a plumber instead of forcing the issue.
When power returns
Do not just turn everything back on. Walk through the house first and look for wet spots, dripping ceilings or damaged pipes. Then open the main valve slowly and check for leaks. Our guide on what to do when power comes back on has a full checklist. If a pipe burst while you were away, report it to your insurer, and take photos before cleaning up.
Prevention for next winter is cheap: insulate exposed pipes, seal gaps in rim joists and crawl spaces, and disconnect outdoor hoses before the first hard freeze.
Quick answers
Does dripping a faucet really help?
Moving water is harder to freeze, so a steady thin drip on exposed pipes helps. It is not a guarantee in very hard cold.
Should I turn off the water if the heat goes out?
If the house is nearing freezing and the outage may last, shutting off the main and draining the lines is the safer choice. Ask a plumber about your specific home.
Can I thaw a frozen pipe with a torch?
No. Open flames and fuel burning devices can start fires and cause carbon monoxide. Use gentle warm air or warm towels, or call a plumber.