Frozen or Burst Pipes in Boston: What to Do Now

How to thaw a frozen pipe safely

If the pipe hasn't split, you can usually thaw it yourself. The goal is gentle, steady heat on the frozen section with a faucet open, so the melting ice has somewhere to go and the running water helps melt the rest. Work from the faucet back toward the frozen section.

If you can't find or reach the frozen section, if it is inside a finished wall or ceiling, or if thawing it reveals a leak, stop and call a plumber. The same goes if more than one pipe is frozen. And if no tap in the house gives any water, the problem may be the service pipe in the yard or the street rather than inside: in Boston, Boston Water and Sewer Commission's 24-hour emergency line is (617) 989-7900; elsewhere, call your town's water department.

1. Open the faucet the frozen pipe feeds, both hot and cold handles.
2. Warm the frozen section with a hair dryer, an electric heating pad, a space heater kept well clear of anything that burns, or towels soaked in hot water. As Boston Water and Sewer puts it, thawing with a hair dryer won't be fast, but it will be safe.
3. Open the cabinet doors under sinks on outside walls so warm room air can reach the pipes.
4. Keep the heat on until full water pressure comes back, then check along the pipe for drips.

• Never use an open flame: no blowtorch, propane or kerosene heater or charcoal stove. The Red Cross, Boston Water and Sewer and the state all say the same, because flame thawing starts house fires.
• Don't leave a space heater running unattended or close to curtains, boxes or insulation.
• Don't use electrical appliances in standing water.

Why Boston pipes freeze, and where

Pipes freeze when cold air reaches them for long enough, not just because the outdoor temperature drops. In Boston houses, the usual suspects are supply lines in exterior walls (especially kitchen and bathroom walls on the north or windward side), pipes in unheated basements and crawl spaces, lines to outside faucets that weren't shut off for the winter, and plumbing in porches, bump-outs and additions built with little insulation. Wind matters as much as temperature, because it drives cold air through gaps in old foundations and around sill plates.

Triple-deckers and row houses add a few risks of their own: a vacant or unheated unit can let pipes freeze for the whole building, and a third-floor unit's pipes often run through the coldest part of the structure. When a freeze is forecast, everyone in the building benefits from knowing where the main shutoff is.

How to stop pipes freezing next time

Most freezes are preventable with a few habits during cold snaps and a few small jobs before winter.

• Keep the thermostat at the same setting day and night during a cold snap, and no lower than 55°F if you go away (Red Cross guidance).
• Let a faucet on an outside wall drip during the coldest nights; moving water is much less likely to freeze.
• Open the cabinet doors under kitchen and bathroom sinks that sit on exterior walls.
• In the fall, disconnect and drain garden hoses, close the indoor valve that feeds each outside faucet, and leave the outside faucet open to drain.
• Seal gaps where cold air gets in around the foundation, sill and where pipes pass through walls. BWSC says most frozen meters are caused by drafts from an open basement door or window.
• Insulate exposed pipes in basements, crawl spaces and garages with foam pipe sleeves; use heat cable on chronic trouble spots.
• Protect the water meter and the service pipe too. In Boston, BWSC makes the owner responsible for keeping both from freezing; it replaces a frozen meter but charges the account a fee based on the meter size.

Going away in winter, and vacant units

An empty house in January is where the worst freeze damage happens, because a burst pipe can run for days before anyone notices. If you're going away during the cold months, keep the heat on at no lower than 55°F, as the Red Cross advises, and ask someone to check the house every day or two, in particular that the heating is still running. For a longer absence, shutting off the main water valve and opening the faucets to drain the lines removes most of the risk.

This matters for insurance as much as for the pipes. The state Division of Insurance warns that burst-pipe cover usually depends on the home having been heated and not left unoccupied, so check what your policy says about vacancy before a long trip. Landlords with an empty unit between tenants, and condo owners who winter elsewhere, should treat the unit the same way: heat on, someone checking, or the water off and the lines drained.

When a frozen pipe is a job for a plumber

Call a plumber if a pipe has split, if you can't find or reach the frozen section, if the whole house has no water, if thawing reveals a leak, or if the same pipe freezes every winter. A plumber can thaw lines inside walls safely with professional equipment, replace the split section (often a few feet of copper or PEX), and reroute or insulate a pipe so it doesn't freeze again.

If a pipe has burst, expect two jobs: the plumbing repair, and drying out the building. A plumber fixes the pipe; a water-damage company dries the walls and floors. Call both quickly, because wet materials grow mold within days.

Frozen pipes, insurance and renters

Freeze damage is a big deal for Massachusetts insurers: the state Division of Insurance says 48.6% of homeowners' claims in 2024 were for non-flood water and freezing damage. Its warning is the one to remember: most policies cover sudden and accidental damage from a burst pipe only if the home was properly heated and not left unoccupied. Keep photos, the failed pipe section and the plumber's invoice. Condo owners should check where their unit's responsibility ends and the association's begins.

If you rent, report a frozen or burst pipe to your landlord immediately and in writing. In Massachusetts the owner is responsible for keeping heat and water working, and if the heat failed, that is part of the same problem.