Why Montana pipes freeze, and how to stop it
Cold alone does not burst a pipe. An unheated pipe in a Montana winter does. What follows is why pipes freeze here, what to check before a cold snap, how to thaw one safely, what to do if it already split, and when the job needs a plumber instead of a hair dryer.
- Last updated 2026-09-24
- Primary sources only
- 6 sources
Why pipes freeze in a Montana winter
How cold does Montana get?
Montana holds the record low for the lower 48 states: −70°F, recorded at Rogers Pass in 1954. Eastern Montana occasionally drops below −30°F. On NOAA's 1991-2020 normals, the average January low is 15 to 18°F in Missoula, Billings and Great Falls; see the Montana plumbing rules page for the exact number in each city.
Does the temperature actually swing that fast here?
Yes. On January 14-15, 1972, a chinook wind raised the temperature at Loma, Montana from −54°F to 49°F, a 103-degree change in 24 hours, the largest ever recorded in the United States. Northeastern Montana also sees blizzards roughly five times a winter on average.
Which pipes actually freeze first?
MSU Extension's housing and environmental health program names the pattern directly: pipes and drains in unheated spaces are the ones that fail, especially in crawl spaces, on exterior walls, and in unheated garages, the parts of a house farthest from the furnace's warm air.
The Montana plumbing code also sets a minimum burial depth for a water service line, well below the frost line, and the exact number is set by each city rather than one statewide figure.
See the burial depth for Missoula, Billings and Great Falls on the Montana plumbing rules pageBefore a cold snap
Cheapest fixes first
Keep the house at one steady temperature
Don't turn the heat down to save money during a cold snap. MSU Extension's advice is blunt about the tradeoff: the extra energy cost is a lot less than paying for a burst pipe and the cleanup that follows.
Open the cabinet doors
Open the doors under any sink on an exterior wall, and the washing machine closet door, so warm house air can reach the pipes inside. A small fan aimed into the space helps move that air around.
Insulate pipes in unheated spaces
Insulate any pipe or drain running through a crawl space, garage, or exterior wall, and close crawl space vents for the winter.
Disconnect and shut off outside faucets
Disconnect garden hoses and shut off the water supply to outside faucets if you can reach that shutoff. If you can't, an insulated faucet cover from a hardware store is the fallback.
Weatherize the walls the pipes run through
Caulk and weather-strip doors and windows, and add insulation in walls and attics. This is the same winterizing Yellowstone County's own emergency management office recommends before a storm, and it matters here for a direct reason: the less cold air reaches a wall cavity, the less it reaches the pipe inside it.
- Yellowstone County Disaster & Emergency Services, Winter Storms (accessed 2026-09-24)
Plan for emergency heat if the power goes out
If a power outage would cut off a thermostat-controlled furnace, plan for emergency heat, a fireplace, wood stove, or properly vented heater, for at least one room. A house that loses heat is what actually freezes pipes, not the outdoor temperature by itself.
- Yellowstone County Disaster & Emergency Services, Winter Storms (accessed 2026-09-24)
Build a basic outage kit and sign up for alerts
Put together flashlights, batteries, water, and food that needs no cooking, and sign up for outage notifications from your utility. NorthWestern Energy pushed the same message ahead of an October 2025 storm, after work upgrading lines across its roughly 25,000-mile Montana system.
Be careful with a dripping faucet
Letting a faucet drip is common cold-snap advice, and MSU Extension says to use it with caution. If that faucet's drain also runs through a cold space, the trickle can freeze in the drain instead and back the sink up rather than preventing anything.
Leaving the house or cabin for winter
Keep the heat running, at a low steady setting
MSU Extension's core recommendation, one steady temperature rather than cutting the heat to save money, applies even more to a place sitting empty for weeks, since nobody is there to notice a slow drop in temperature until a pipe has already split.
Or drain the system instead
If the heat will truly be off all winter, shut off the main water valve and drain the supply lines by opening the lowest faucet in the house (see the water shutoff steps below). Water that isn't in the pipe can't freeze and split it.
Disconnect hoses and outside faucets before you go
Same as before any cold snap: disconnect garden hoses and shut off the water supply to outside faucets, or fit an insulated cover if the shutoff isn't reachable.
If a pipe is frozen
No open flame
- 01
Find where it's frozen
Almost always a crawl space, an exterior wall, an unheated garage, or the point where a line enters the house from outside.
- 02
Open the faucet on that line
Running water, even a trickle, speeds up the thaw and relieves the pressure building up behind the ice.
- 03
Warm the pipe gently
MSU Extension recommends an electric heater or a hand-held hair dryer aimed at the frozen section, working from the faucet end back toward the blockage.
- 04
Keep the heat source safe
Keep any heater away from combustible material, never leave a space heater unattended, and never run an unvented kerosene or gas heater in an enclosed space without ventilation.
- 05
Never use an open flame
MSU Extension does not recommend open-flame propane torches for thawing pipes. A torch aimed into a wall cavity or under a floor is a way to start a house fire, not just thaw a pipe.
- 06
Call a plumber if you can't reach it
MSU Extension's own description of thawing pipes in wall cavities and hard-to-reach spots is that it "can be complicated and difficult." That's the point to call a plumber instead of keep guessing.
If it already split
Shut off the water first
If you are on Missoula's municipal water system, the city runs a 24-hour line for exactly this: 406-552-6700, to report a water emergency or get help shutting off water at the meter or street. In a life-threatening emergency, call 911 instead.
- City of Missoula, Emergency Preparedness (accessed 2026-09-24)
How to shut off the water in a Montana home
Shutting the main valve stops the damage while you wait. In most Montana houses the main shutoff is inside, where the water service comes through the foundation, because an outside valve would freeze.
- 01
Find the main shutoff
Look where the water line enters the house: the basement or crawl space wall on the street side, near the water heater, or in a utility room. Older Montana homes often have it in the crawl space rather than a basement.
- 02
Turn it off
A round handwheel turns clockwise until it stops. A lever-style ball valve turns a quarter turn so the handle sits across the pipe rather than along it.
- 03
If you cannot reach the main, use the local stop
A single leaking toilet, sink or water heater has its own shutoff on the supply line right at the fixture. Turning that one off isolates the fixture without cutting water to the rest of the house.
- 04
If there is no interior valve, use the curb stop
The curb stop sits in a small metal or plastic box at the property line, usually under a round lid marked water. It takes a long curb key rather than a hand, so this is normally the utility's job to operate.
- 05
Open a low faucet to drain the lines
With the supply off, open the lowest faucet in the house. That drops the pressure in the pipes and lets the standing water out at a controlled point instead of through the leak.
- 06
Cut power if water is near electrical
If water is running near outlets, a panel, or a light fixture, switch off the breaker for that circuit before going into the water.
When to call a plumber
- No water flows again after a thaw attempt.
- You find a split, a crack, or an active leak.
- The frozen section is inside a wall or a slab and you cannot reach it.
- Heat tape on the pipe is old, damaged, or was not installed to the manufacturer's instructions.
Sources
- MSU Extension, "Keep pipes from freezing this winter" (Mike Vogel) (2013-12-03)
- NorthWestern Energy, "NorthWestern Energy urges safety ahead of Montana winter storm" (2025-10-10)
- City of Missoula, Emergency Preparedness (water emergency line) (accessed 2026-09-24)
- Yellowstone County Disaster & Emergency Services, Winter Storms (accessed 2026-09-24)
- National Weather Service, Billings/Miles City winter weather page (accessed 2026-09-24)
- NOAA NCEI, Montana State Climate Summary 2022 (2022)
The National Weather Service's Billings/Miles City office publishes live snow and wind chill forecasts rather than a fixed threshold, so it is linked above for current conditions during a storm rather than quoted for a number. Burial depth, frost depth, and January average low figures for Missoula, Billings and Great Falls are sourced separately on the Montana plumbing rules page rather than repeated here.
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