How Do I Thaw a Frozen Pipe Safely?

Root cause

Before thawing anything, you need to know where the ice actually is. Pipes running through unheated spaces — against exterior walls, in basements, attics, garages, or crawlspaces — are the most exposed to cold and the most likely freeze points.

30-second check

Turn on faucets throughout the house — a trickle or no flow at all points to a freeze somewhere upstream of that fixture. Check pipes in unheated areas and along exterior walls for visible frost or a noticeably cold section by touch.

Tools & materials

A flashlight for checking crawlspaces or under cabinets.

Step-by-step

1. 1 Test every faucet in the house and note which ones have reduced or no flow.
2. 2 Trace the supply line for affected fixtures back toward the main line, checking for exposed runs through unheated spaces.
3. 3 Look and feel for visible frost, a cold-to-the-touch section, or a section that looks different from the rest of the pipe.
4. 4 Once located, open the nearest faucet on that line partway before you begin thawing — this relieves pressure as ice melts instead of trapping it.

Root cause

Once located, a frozen but intact pipe can be thawed with gentle, even heat applied along its length. The specific danger here is thawing too fast or too intensely — concentrated heat can soften plastic pipe or weaken a soldered joint, and closed fixtures downstream can trap the expanding meltwater instead of letting it relieve pressure.

30-second check

Confirm the nearest faucet on the affected line is open partway before starting — this is what lets meltwater flow instead of building pressure behind the ice.

Tools & materials

A hair dryer or electric heating pad, towels to catch drips.

Step-by-step

1. 1 Open the nearest faucet on the affected line partway, so water can flow as soon as the ice starts to clear.
2. 2 Starting at the faucet end and working backward toward the frozen section, apply gentle heat with a hair dryer on low-medium, moving it continuously along the pipe rather than holding it in one spot.
3. 3 Continue until full water pressure returns at the open faucet.
4. 4 Once flowing normally, reduce that faucet to a slow drip until the cold snap passes, which helps prevent the same section from refreezing.
5. 5 Never use an open flame, a propane torch, or any high-intensity heat source — these can scorch materials, weaken joints, or ignite nearby debris.

Root cause

Pipes freeze when they're exposed to sustained cold without enough insulation or heat nearby — a genuinely preventable situation in most homes with a few inexpensive, low-effort habits, rather than something to just wait out every winter.

30-second check

Identify which pipes are actually at risk — anything in an unheated basement, attic, garage, crawlspace, or running along an exterior wall.

Tools & materials

Foam pipe insulation sleeves (a few dollars per length).

Step-by-step

1. 1 Wrap exposed pipes in unheated areas with foam pipe insulation, available inexpensively at any hardware store.
2. 2 During a cold snap, let vulnerable faucets drip slightly — moving water is much less likely to freeze than still water.
3. 3 Keep your thermostat set to the same temperature day and night during cold weather rather than lowering it overnight.
4. 4 If you'll be away during winter, leave the heat on, set no lower than 55°F.
5. 5 Open cabinet doors under sinks on exterior walls during a cold snap to let household heat reach the pipes inside.

Root cause

If a frozen section has already split or cracked, thawing it will simply let water flow directly through the break rather than through the pipe — that's an active leak, not a blockage to clear. Separately, some frozen sections run inside walls, under slabs, or in genuinely inaccessible locations where DIY thawing isn't realistic or safe.

30-second check

You see or hear active water flow somewhere it shouldn't be, notice a wet ceiling or wall, or the frozen section is inside a wall or slab where you can't reach it directly.

What a professional actually does

A plumber shuts off water at the main immediately if needed, locates and repairs or replaces the burst section, and can assess whether other exposed pipes in your home are at similar risk going forward.