How To Thaw a Frozen Pipe Safely
Shut the main, open the affected tap, then warm the whole area gradually working from the tap end back toward the ice. Never use an open flame, a blowtorch or a propane heater on a pipe.
What to do right now
Do these first. None of them need tools or plumbing knowledge, and they limit what this ends up costing you.
Stop and get out if any of these are true
Never use an open flame, a blowtorch, a propane heater or any concentrated flame source on a frozen pipe. It is a leading cause of house fires during cold snaps, and it can flash trapped water to steam inside a sealed section and rupture it violently.
- Shut the main before you startIf the pipe split while frozen, the ice is currently the only thing holding it closed. Thawing with the water on means it begins flowing the moment it clears.
- Open the affected tapIt gives melting ice somewhere to go, relieves pressure as the plug releases, and tells you the moment flow returns.
- Warm the area, not the spotA space heater in the room, or a hair dryer moved constantly. Work from the tap end back toward the frozen section so meltwater can escape rather than being trapped behind more ice.
- Reopen the water slowly and watchOnce flow returns, open the main gradually and stay with the pipe while the system refills. This is the moment a split reveals itself.
Does this need a plumber tonight?
- A frozen pipe you cannot reach or see
- A frozen section inside a wall or under a floor
- A frozen main or buried service line
- Any bulge or deformation in the pipe
- No water at all with the house below freezing
- An accessible run you can reach and warm safely
- A frozen outside line you have isolated and drained
Why direction matters
Working from the tap end back toward the ice gives the melting water a route out. Starting in the middle of a frozen section traps meltwater between two ice plugs, and that is how thawing causes a burst.
The trapped water has nowhere to go as it expands, and pressure builds in a closed section. That is the mechanism behind most thawing related failures and it is entirely avoidable by working in the right order.
The open tap serves the same purpose at the system level. It guarantees an escape route for both water and pressure throughout.
When to stop and call
If the frozen section is inside a wall, under a floor, on the buried service line, or if you cannot locate it at all. Also if flow does not return after a reasonable effort.
Concealed sections cannot be warmed safely from outside without heating the structure around them, and the temptation at that point is to reach for something hotter, which is exactly the wrong move.
There is no shame in stopping. A thawing job that goes wrong is considerably more expensive than the call out.
Questions people ask about this
Can I use a hair dryer?
Yes, kept moving and never held in one place. What you must not use is any open flame, including a blowtorch or a propane heater aimed at the pipe.
How long should it take?
Usually between twenty minutes and an hour for an accessible run with steady warmth. If nothing has changed after that, the ice is probably somewhere you cannot reach.
The water came back but now it is leaking.
The pipe split while frozen and the ice was holding it. Shut the main again and call. This is exactly why the first instruction is to shut the water off before thawing.
If that is not quite what you have
Not sure how urgent this is?
Describe what you can see and hear. We will tell you whether it needs someone tonight, and what to do in the meantime either way.
Or send it over
Four things and a photo.