How to keep your pipes from freezing this New England winter

Every January I get the same call: water pouring through a ceiling because a pipe froze, split, and then thawed. The good news is that frozen pipes are almost entirely preventable. After years of winters across Greater Boston, here's exactly what I tell homeowners to do.

Why pipes freeze (and why they burst)

When water freezes it expands. Inside a closed pipe, that expanding ice pushes water toward the closed end — usually a faucet — and pressure builds between the ice blockage and the tap. It's that trapped pressure, not the ice itself, that splits the pipe. The pipe often holds until it thaws, which is why a burst frequently shows up after the cold snap, not during it.

Which pipes are most at risk

The vulnerable pipes are the ones exposed to cold air or running through unheated space:

• Pipes in unheated basements, crawl spaces, attics and garages
• Lines along exterior walls with little or no insulation
• Outdoor hose bibs and sprinkler/irrigation lines
• Plumbing in additions or rooms that were never well heated

Before a deep freeze

A little prep in the fall saves a lot of grief in January:

• Insulate exposed pipes with foam sleeves, especially in the basement and garage.
• Seal drafts near pipes — gaps around the sill, vents and where lines pass through walls let freezing air right onto the pipe.
• Disconnect garden hoses and shut off and drain outdoor hose bibs and irrigation lines.
• Find your main water shut-off now and make sure it turns freely. In an emergency, seconds matter.

During a cold snap

When temperatures drop into the teens or below, especially with wind:

• Let vulnerable faucets drip. A trickle of moving water is much harder to freeze and relieves pressure.
• Open cabinet doors under sinks on exterior walls so room heat reaches the pipes.
• Keep the heat on, at least 55°F, even if you're away. Never let the house go cold to save a few dollars.
• Keep the garage door closed if there's plumbing in or above it.

If a pipe is already frozen

If you turn on a tap and only a trickle comes out, you likely have a freeze starting. Act calmly:

• Open the faucet so water and steam can escape as the ice melts.
• Apply gentle heat — a hair dryer, heat lamp or towels soaked in warm water. Work from the faucet end back toward the cold spot.
• Never use an open flame or a blowtorch. It's a fire risk and can damage the pipe.
• If a pipe has already burst, shut your main water valve immediately and call.

When to call a plumber

Call if you can't locate the freeze, can't get the pipe thawed, find a pipe has already split, or you simply want it handled right. We can also help you winter-proof the at-risk spots before the cold hits — and if your heat or hot water quits in the middle of it, that's something we handle too. For everyday repairs and repipes, see our plumbing services.