Frozen Pipe Repair
The whole winter sequence, including repairing whatever the ice split.
Learn moreWinter failures
Thawing a Pipe Is a Slow Job Done Fast
Ice in a water line is one of the few plumbing problems where the wrong tool causes more damage than the original fault. Thawing is about finding the plug, applying heat in the right direction at the right rate, and being ready for what the water does when it starts moving again.
Lines are open right now:
(833) 472-2088
No water and cold outside? Close the main, then call.
Never open flame
Torches near framing and insulation start fires. Not used, ever.
Ice located first
Heating the wrong three feet of pipe accomplishes nothing but time.
Tap open throughout
Meltwater and pressure need somewhere to go while heat is applied.
Watched afterwards
Flow returning is when a split shows itself. Someone should be there.
Scope
This page is about one stage of a winter call
Thawing is the operation of getting ice out of a line. It is not the same job as repairing the split that ice may have left behind, and it is worth keeping them separate in your head, because on perhaps half of cold-snap calls, the pipe thaws intact and there is nothing further to do beyond addressing why it was cold in the first place.
If you have lost water in freezing weather and want the whole picture, frozen pipe repair covers the full sequence. If water is already escaping into the building, that is burst pipe repair and a call rather than reading. This page is for the middle case: nothing is leaking, nothing is flowing, and something has to be done about the ice.
One decision belongs to you before anyone arrives. Close the main. A thawing job with the water off is controlled; a thawing job with the water on can turn into a flood the instant the plug releases, and nobody can predict which it will be.
Why not just wait for warm weather?
Because a passive thaw is an uncontrolled thaw. If the pipe split under pressure while frozen, the ice is the only thing holding the water back, and it will let go on its own schedule, quite possibly while the house is empty. Thawing deliberately, with the main closed and someone watching, is how that risk gets managed.
Tell us which taps are dead, that alone narrows down the ice.
Diagnosis
Finding the plug before spending an hour heating the wrong pipe
Ice does not announce itself. On a long run through a crawl space, the frozen section might be eighteen inches of a forty-foot line, and heat applied anywhere else is heat wasted.
The fixture map is the first tool and it costs nothing. Which taps are dead, which still run, and whether hot and cold are both affected together tell the plumber where the plug sits relative to the branches. Cold only, at one bathroom, means a branch freeze near that bathroom. Everything dead in the house means the freeze is upstream of the first split in the piping, the crawl space, the entry point or the meter.
After that it is physical. Surface temperature readings along the run find the cold section: ice sits well below the surrounding pipe and shows up clearly. Frost or condensation rings on a fitting, a section that has visibly sweated and refrozen, and the geometry of the house all narrow it down. In a vented crawl space, the answer is very often within a few feet of a vent or a foundation penetration, because that is where the moving cold air is.
Where the line disappears into a wall or under a slab, the diagnosis becomes inferential: which fixtures fail, how the piping must run to reach them, and where that run passes through cold. Opening the smallest possible access, in the most likely place, beats opening three optimistic holes.
Tools
Four ways heat gets into a frozen line
Controlled electric thawing. Low-voltage, high-current equipment clamped to either side of the frozen section warms the pipe wall itself, from the inside out along the metal. It is the fastest method on accessible metal pipe and works on runs you cannot get a heat source around. It does not work on plastic pipe, and it requires a continuous metallic path, so a stretch of PEX in the middle of a copper run rules it out.
Warm air. Unglamorous and often correct. A heat source warming the whole space, a crawl space, a cabinet, a utility closet, rather than one spot on the pipe thaws slowly but very safely, and it treats the actual problem, which is a cold volume of air rather than a cold pipe.
Heat tape and pipe wrap. Thermostatically controlled tape applied along the frozen run, which then stays in place as the permanent fix for a section that cannot be moved or insulated properly. Two jobs for one visit.
Steam thawing. Used mainly on buried lines and long inaccessible runs: a hose fed into the pipe delivers steam to the ice face and melts it back progressively. It is specialised equipment, and it is the method that reaches a frozen service line under a driveway without excavating it.
What is never used
Open flame of any kind. A propane torch in a crawl space full of dry framing and paper-faced insulation is how houses burn down in January, and it is not a hypothetical, it happens somewhere in the mountain west every winter. Beyond the fire risk, flame heats a small area extremely fast, which can flash steam inside the pipe and rupture a line that would have thawed intact. Also avoided: kerosene salamanders pointed at the underside of a floor, and heat guns held stationary against plastic pipe.
Thawing goes faster when nobody has to guess where to start.
Underground
When the frozen section is under the ground
Buried water services normally sit below the frost line, and in most of Idaho they stay liquid all winter without anyone thinking about them. The freezes that do occur happen at the transitions, and they behave differently from anything inside the house.
The vulnerable points are the meter pit, the shallow run between the pit and the foundation, the penetration into the crawl space, and any section that a previous owner buried optimistically shallow. A run of unusually cold weeks with little snow cover is the classic trigger: snow is an insulator, and a hard cold snap on bare ground drives frost deeper than the same temperatures with a foot of snow on top.
Thawing a buried line is a steam or electric job, not a warm-air one, and it takes time, measured in hours rather than minutes. It is also the situation where responsibility gets divided, so it is worth being clear about the line: the water utility generally owns the main and the meter, and the homeowner generally owns the service line from the meter to the house. If the freeze is on the utility's side, the utility deals with it, and the useful thing we can do is help you work out which side it is on so you are not paying to fix someone else's pipe.
If the same buried section freezes in consecutive winters, thawing it annually is not a plan. Reburying at depth, insulating the shallow section, or rerouting it is the actual answer, and summer is when that work should be scheduled, see main water line repair.
Afterwards
The five minutes after the water starts moving
Thawing is the part everyone focuses on. The part that determines whether the day ends well is what happens immediately afterwards.
As the plug melts, the line is brought back up under pressure slowly and then watched, at the thawed section, at every fitting either side of it, and at the ceiling and walls below the run. A split that opened while the pipe was frozen will show itself now, and the difference between catching it in the first thirty seconds and finding it an hour later is measured in flooring.
Then the fixtures are run, hot and cold, to clear air and any debris the event stirred up. Air in the lines after a thaw is normal and clears in a few minutes of running. Discoloured water for a short while, particularly in older galvanized systems, is also normal, the ice and the sudden flow disturb scale on the pipe wall.
Last comes the conversation about why. A pipe that froze this January will freeze next January unless the vent that was left open gets closed, the insulation gets fixed properly, or the run gets moved. That conversation is short, it costs nothing, and it is the difference between one visit and an annual tradition. Freeze protection and winterization is where it usually leads.
Same buried line every winter? That deserves a summer fix.
How it runs
A thawing call, step by step
Deliberate pace, in a fixed order. Speed comes from not doing the wrong thing first.
Main off, tap open
The main gets closed before heat goes anywhere near the pipe, and the nearest fixture is opened so meltwater and pressure have an exit.
Heat from the fixture back
Working from the open end toward the plug, so melting ice can escape instead of being trapped between two frozen sections.
Repressurise and watch
Water is brought back slowly with eyes on the thawed section and everything below it. Any split shows up in the first minute.
Coverage
Thawing calls follow the cold
Eastern Idaho and the mountain valleys generate the most thawing work per household, and the Panhandle's wet cold does its own damage; the Treasure Valley produces the highest raw volume during a hard snap. Every community on this site is covered, though a storm in the mountains stretches the window.
Questions
Pipe thawing questions
An accessible branch line with electric equipment on it is often flowing in twenty to forty minutes. A crawl space main takes longer. A buried service line, or a run under a slab or behind finished wall, can take several hours, because the heat has to travel through material that is not designed to conduct it. Pushing more heat at it faster is how a repairable freeze becomes a burst pipe.
A sealed electric heater on a dry surface, at a sensible distance from framing and insulation, with an eye on it, is genuinely one of the safer things a homeowner can do. What causes fires is fuel-burning equipment, propane, kerosene, salamanders, left running in an enclosed space under a floor. Those also produce carbon monoxide, which is its own hazard in a space connected to the house air.
Because nobody can tell whether the frozen pipe has already split. The ice is acting as a plug; when it releases, either water flows normally or it pours out of a crack. With the main closed, the worst case is the water already in the pipe. With the main open, the worst case is the whole house supply at full pressure.
It can be partial obstruction from ice, and it can also be several other things entirely, a failing pressure regulator, a clogged whole-house filter, a partially closed valve, or scale in old galvanized supply. Pressure loss without a freeze event usually has a different cause, and it is worth diagnosing rather than assuming winter is to blame.
Yes, and they are a distinctly different job. Drains freeze when a shallow or poorly sloped line holds standing water, and they are more common at cabins, in crawl space plumbing and on lines running through unheated additions. The thawing methods overlap; the fix afterwards is usually about slope, insulation or rerouting rather than about pressure.
PEX tolerates freezing far better than copper, it stretches rather than splits, and it tolerates gentle warming fine. What it does not tolerate is direct high heat: a heat gun held against it, or flame anywhere near it, will deform or melt it. Electric thawing equipment cannot be used on it at all, because it needs a continuous metal path. Warm air is the method of choice.
Generally the utility owns the main and the meter, and the property owner owns the service line from the meter to the house, but the exact demarcation varies by city and district in Idaho, and it is worth confirming with your provider. If the freeze looks like it sits on their side, we will tell you so rather than bill you for it.
Usually debris. Ice and sudden flow dislodge scale and sediment, which then lodges in the nearest restriction, most often an aerator or a fixture cartridge. Cleaning or replacing those solves it. If pressure is low at everything on one branch instead, the line may be partially collapsed or still partly frozen further along.
Cold-snap slots go early in the day. Calling sooner helps.
Ice in the line? Don't reach for a torch.
Close the main, open the nearest tap, and call. Thawing done in the right order is a routine visit, done in the wrong order it becomes a repair, a claim and a restoration crew.
(833) 472-2088