Frozen Pipes: What to Do Before and After the Thaw

The leak may begin after the freeze

A faucet that stops flowing during a cold snap is a warning, but the largest water release may not appear until temperatures rise. Ice can split a pipe while also blocking the opening. When the ice melts, full water pressure reaches the crack.

If one fixture has no flow, keep the faucet open slightly, locate the main shutoff, and inspect accessible piping. If you see a bulge, split, or water staining, shut off the water and call a plumber. If water is already escaping, treat it as an emergency.

Find the vulnerable section without damaging it

Frozen sections often occur where plumbing crosses an exterior wall, crawlspace, unheated garage, attic, cabinet back, or sill area. Compare nearby fixtures: if one faucet is affected and another works, the blockage is probably on a branch rather than the whole service.

Safe warming is slow and controlled. Warm the room, open cabinet doors, and use a hair dryer or portable heater only if the appliance is dry, attended, and used according to its instructions. Start near the faucet and move toward the cold section so melting water has an exit.

Never use a torch, open flame, charcoal heater, or improvised high-heat device. Fire and carbon-monoxide risks are more serious than the frozen pipe.

When to stop and call

Professional help is appropriate when the frozen area is concealed, the main service is affected, a pipe is visibly distorted, no safe heat source is available, or the homeowner cannot monitor the thaw. Call immediately if water reaches electrical equipment, ceilings begin to sag, or a gas appliance or vent is involved.

A plumber may isolate the branch, inspect joints and fittings, pressure-test the repaired section, and look for a second freeze point. Opening a wall may be necessary, but careful diagnosis can reduce unnecessary demolition.

Repairing the break is only half the job

A permanent repair should address both the split and the condition that allowed freezing. Depending on access and system condition, that can mean replacing a short damaged section, moving a line inward, insulating the cavity, sealing air leaks, or adding approved heat protection. Repeated patches in the same exposed run can signal that the routing—not just one fitting—is the problem.

Ask the contractor to explain:

• which section froze and why;
• whether adjacent fittings were stressed;
• what material will replace the damaged pipe;
• whether the line can be rerouted or better protected;
• whether local permits or inspection apply; and
• what work belongs to a plumber versus an insulation, electrical, or restoration contractor.

Reduce risk before the next cold spell

Cold-weather preparation should focus on exposure and air movement:

• disconnect garden hoses and drain exterior faucets where the system allows;
• insulate accessible piping in unheated areas;
• seal drafts around penetrations without burying valves or unsafe equipment;
• keep indoor heat on and follow public-safety guidance if leaving the house;
• open sink cabinets on exterior walls so room air can reach piping; and
• know how to shut off the main water supply.

Allowing a small stream from a vulnerable faucet can help in some conditions, but it is not a substitute for insulation, heat, and corrected routing. Follow utility or emergency guidance for the specific weather event.

Water, electricity, and cleanup

Do not enter water that may be energized. Do not use extension cords or heaters in a wet area. Wet drywall and insulation can conceal damage even after the pipe is repaired; drying and remediation may be separate from plumbing work. Photograph the affected area before cleanup when it is safe to do so, and contact the insurer promptly if damage is substantial.

Philadelphia checks

PWD maintains the water main in the street. The service line from the main into the house and all of the plumbing inside are the owner's responsibility, so a break on the owner's side needs a licensed plumber. Report water coming up in the street or sidewalk to PWD.

Plumbing permits in Philadelphia are issued by the Department of Licenses and Inspections (L&I) under the Philadelphia Plumbing Code, and permitted plumbing work is done by a Philadelphia-licensed master plumber. Pennsylvania home-improvement (HIC) registration is not a plumbing license. Ask who will pull the permit and confirm the license before work starts. This directory does not endorse a listed business.

Sources

1. Preventing and Thawing Frozen Pipes, American Red Cross
2. How to Prevent Your Pipes From Freezing and Bursting, Consumer Reports
3. Winter Weather Ready, Insurance Institute for Business & Home Safety
4. Apply for a Uniform Construction Code Building Permit, Pennsylvania Department of Labor & Industry
5. Contractor Licensing, Pennsylvania Department of Labor & Industry
6. Home Improvement Contractor Registration, Pennsylvania Office of Attorney General
7. How to Prevent Frozen and Burst Pipes, This Old House
8. Customer Responsibilities, Philadelphia Water Department
9. Damaged water mains & pipes: water infrastructure emergencies, Philadelphia Water Department
10. PB_022 FAQ — Summary of 2018 Philadelphia Plumbing Code Amendments, Philadelphia Department of Licenses and Inspections