Pipes when the heat is off

Why pipes burst

Water expands as it freezes. The ice plug itself rarely splits the pipe. The pressure trapped between the ice and a closed tap does. That is why a frozen pipe often leaks only when it thaws, and why relieving pressure matters.

Pipes most at risk run through outside walls, crawl spaces, attics, garages and under sinks on outside walls.

Do these before winter

1. Find the main water shutoff and turn it off and on once. A valve that has not moved in ten years may not move in an emergency. Show everyone in the house where it is.
2. Ask a plumber to walk you through shutting down and draining your system, and write the steps down. Water heaters, boilers, wells, sprinkler lines and water softeners each have their own rules, and doing it wrong can ruin equipment.
3. Insulate exposed pipes in unheated spaces with foam sleeves. See pipe insulation on Amazon.
4. Disconnect garden hoses and shut off outdoor taps from inside if you can.
5. Know where your water meter and floor drains are.

If you rent, you do not own the plumbing. Ask your landlord what the plan is and who to call.

In a short outage

While the house is still well above freezing:

• Keep the heat in. Doors and windows shut, curtains closed at night.
• Open the cabinet doors under sinks on outside walls so room air reaches the pipes.
• Let cold taps drip on the lines most at risk. Moving water freezes more slowly, and an open tap relieves pressure. This only helps while you still have water pressure, and on a well it uses up the tank.
• Catch the drips in a bucket. It is water you may want.

When the house is going to freeze

If the outage will be long and the inside of the house is heading toward 0 °C (32 °F), dripping is not enough. The safer move is to shut the water off at the main and drain the system the way your plumber showed you. In general that means main valve off, taps open from the top of the house down, toilets flushed. Shut off the power or gas to the water heater before it is drained, because a heater that fires while empty is destroyed.

Drains and toilets hold water in their traps as well. Plumbers use non-toxic RV or plumbing antifreeze for those, never automotive antifreeze. See RV plumbing antifreeze on Amazon.

Before you drain everything, fill your drinking water containers. Once the system is empty, the taps are no use to you.

If a pipe has already frozen

• Shut the water off at the main if you see a split or a leak, or cannot watch the pipe.
• Open the tap the pipe feeds, so melting water has somewhere to go.
• Warm the pipe gently from the tap end back toward the frozen part, with warm towels or, once power is back, a hair dryer.
• Never use a torch, a heat gun or any open flame. This is a common cause of winter house fires.
• Stay out of standing water near anything electrical, and call a plumber.

When the heat returns

Turn the water back on slowly, with someone watching each floor for leaks. Do not turn a water heater back on until its tank is full. Check again an hour later, since some splits only open up once the ice behind them melts.