Updated October 27, 2026
To thaw a frozen pipe, open the faucet it feeds, know where the shutoff is before you start, then warm the pipe slowly with a hair dryer, an electric heating pad or towels soaked in hot water. Never use a torch or any open flame. In Northern Virginia, if the pipe splits as it thaws or you can’t find the frozen spot, the after-hours plumbing visit is $250, and $49 during regular hours.
Here’s the part people miss. A frozen pipe usually doesn’t leak while it’s frozen, because the ice is the plug. Fairfax County Fire and Rescue says it straight: “In most cases, the actual break doesn’t appear until the water begins to thaw.” So the thaw is the moment to stand next to the shutoff, not the moment to walk away and let it sort itself out.
How to thaw a frozen pipe, step by step
Do these in order. You need a hair dryer or a heating pad, a few old towels, a bucket and a flashlight.
- Make sure it’s frozen. The Red Cross says if you turn on a faucet and only a trickle comes out, suspect a frozen pipe. Then try every other faucet in the house. If one pipe froze, others may have too.
- Find the frozen stretch. Follow the line back from the faucet. The likely spots are pipes against outside walls and the spot where the water line comes through the foundation, plus anything in a crawl space, garage, attic or a sink cabinet on an outside wall. Sometimes you can feel the cold spot or see frost on the pipe.
- Find the shutoff before you add heat. Know where the main valve is and that it turns. If you’ve never looked, here’s how to find your shutoff valves. Fairfax County Fire and Rescue also says to know where the water heater’s power or gas shutoff is.
- Open the faucet. Open the one that pipe feeds, hot and cold if it’s a mixer. The Red Cross says running water helps melt the ice as it starts to move, and an open faucet gives the water somewhere to go.
- Add gentle heat. A hair dryer moved back and forth along the pipe, an electric heating pad wrapped around it, towels soaked in hot water, or a portable space heater set well away from anything that can burn. Start at the faucet end and work back toward the ice, so the water that melts has an open path out.
- Keep going until the pressure is back. The Red Cross says to keep the heat on until full water pressure returns. A trickle isn’t done. When it runs full, walk the whole line with a flashlight and look for drips, then check again in an hour.
Keep the hair dryer and any cords out of standing water, and stay with a space heater while it’s running.
Shutoff open or closed while you thaw? The two sources split here, so this is how we put them together. Fairfax County says to shut the valve to that pipe first, and the water heater too if it’s the hot line, then thaw it slowly. The Red Cross says keep the faucet open so water helps melt the ice. If the frozen stretch is out in the open where you can watch it, open the faucet, warm it, and keep someone standing at the main shutoff. If it’s inside a wall or above a finished ceiling, where a split would leak where you can’t see it, close the shutoff first, open the faucet, warm the room, and when you think it’s clear, open the shutoff slowly and watch the ceiling and the wall.
Will a frozen pipe burst when it thaws?
Not every time, but if it’s going to leak, that’s when you’ll find out. The Red Cross explains that water expands as it freezes, and the pressure that builds can break a metal or plastic pipe no matter how strong it is. The split happens while it’s frozen. The water shows up once the ice lets go. Here’s how to read what you see as it thaws.
Swipe to see all columns →
Swipe to see all columns →
| What you see as it thaws | What it usually means | What to do |
|---|---|---|
| Full pressure comes back, no drips anywhere on the line | It thawed without splitting | Check again in an hour, then fix why it froze (keeping pipes from freezing) |
| Water dripping or spraying from the pipe | It split while it was frozen | Close the main shutoff, then what to do when a pipe bursts |
| A stain spreading on a ceiling or wall | A split inside the wall or ceiling | Close the main shutoff. Keep clear of outlets, switches and light fixtures near the wet spot |
| Pressure stays weak after the pipe you warmed feels warm | More ice further along, or a split upstream | Keep looking along the line, or call |
| Outside faucet works, then water shows inside when you use it | The spigot split inside the wall | Shut that line off and read outdoor spigot freeze and burst |
Fairfax County Fire and Rescue says the department answers hundreds of minor water pipe breaks every year. It also says to call the fire department if water gets into or near electrical outlets or the electric panel, or threatens a pilot light or the power to a water heater or furnace. Anything else, close the shutoff and call a plumber.
$29 Water Test and Plumbing Safety Check
A licensed plumber tests your water's hardness at your kitchen table, in grains per gallon, checks your water heater's age and health and walks the plumbing with photos. Book the $29 test
What never to use on a frozen pipe
No flame. Every source on this agrees.
- No torch. Fairfax County Fire and Rescue says a torch thaws the water too fast and weakens the pipe, which almost always ends in a break.
- No kerosene or propane heater, no charcoal stove, no other open flame. That’s the Red Cross list. Loudoun Water says the same: never thaw a pipe with an open flame.
- No heat jammed against the pipe and left alone. A space heater belongs where it can’t touch towels, boxes or insulation, and you stay in the room.
Here’s the plumber’s reason on top of theirs. A frozen pipe sits against framing, insulation and the back of drywall, the stuff that burns. A flame pointed into that space is a house fire waiting for a draft. Slow heat is safer, and slow is also how the pipe comes through without splitting.
How long does a frozen pipe take to thaw?
No source we trust puts a number on it, because it depends on how cold it got, how much of the line froze and where it is. A short stretch of exposed copper under a sink is a different job from a line frozen inside an outside wall.
Here’s our rule of thumb. If steady, gentle heat on the stretch you can reach brings no water at all after half an hour or so, you’re probably warming the wrong spot or the ice is somewhere you can’t reach. That’s when to call.
And don’t wait for it to thaw on its own. It will, once the weather breaks or the house warms up. But that tends to happen while you’re at work or asleep, and if the pipe split, nobody’s standing at the shutoff when the water starts.
When the frozen pipe is inside a wall or ceiling
You can’t put a hair dryer on a pipe you can’t see, so you warm the room instead. Close the main shutoff first, for the reason above. Then:
- Turn the heat up in the house and leave it there. The Red Cross says to keep the thermostat at the same setting day and night in cold weather.
- Open the sink cabinet doors on outside walls so the warm room air reaches the pipes.
- Set a portable space heater in the room facing that wall, well clear of furniture, curtains and anything that can burn.
- Don’t cut the wall open just to thaw it. Warm the room, wait, and let us open it only if it split.
When you turn the water back on, open the shutoff a little at a time and watch the ceiling below and the wall itself. A stain or a drip means it split. If you think there’s a leak but can’t see it, that’s a leak detection job.
If no faucet in the house works: the meter or the line coming in
One faucet out means one pipe. Every faucet out usually means the freeze is where the water line comes into the house, which the Red Cross names as a likely spot, or at the water meter.
The meter belongs to your water utility, not to you. Loudoun Water says to contact them if you think your meter is frozen (their daytime and after-hours numbers are on their frozen pipes page), and not to open the meter box yourself, because that can damage the meter and bring fines. If you’re on another water system, call that utility about the meter. The pipe on your side of the meter is plumbing, and that part is ours.
When to call a plumber for a frozen pipe
The Red Cross says to call a licensed plumber if you can’t find the frozen spot, can’t reach it, or can’t thaw it. We’d add four more:
- It split. Close the main shutoff first.
- Water is near outlets, the panel, or the water heater or furnace. Shut the water off, stay clear, and call the fire department if it’s touching the electrical, the way Fairfax County Fire and Rescue says.
- Nothing comes out anywhere and the meter isn’t frozen.
- The same pipe froze last winter too. Fairfax County suggests rerouting pipes out of the cold spots, and that’s a job we do.
Our plumbing diagnosis visit is $49, and $250 after hours. Most water pipe repairs inside the house run $450 to $650; the pipe repair page has what that covers. We answer day or night at (703) 997-9757, and the emergency plumbing page explains how after-hours visits work. If it can wait for regular hours, book online.
After it thaws: keep that pipe from freezing again
A pipe that froze once is telling you where the cold gets in. The full list is in how to keep pipes from freezing, but the short version from the Red Cross and Loudoun Water:
- Keep the thermostat at one setting, day and night, in a cold snap, and no lower than 55 degrees if you’re away.
- Open the sink cabinet doors on outside walls.
- On the coldest nights, let cold water trickle. Loudoun Water says from the faucet farthest from the main shutoff and at the highest point in the house. Fairfax County is fair about it: a trickle may or may not keep a pipe from freezing.
- Shut off and drain the outside faucets before the first hard freeze (how outdoor spigots freeze and burst).
If the power goes out in January, the whole house becomes the cold spot; here’s how to protect heat and pipes in a winter power outage. And if you want to know what else in the house tends to cause the big leaks, read the parts that flood houses.
Frozen pipe questions
How do you thaw frozen pipes?
Open the faucet the pipe feeds, know where the main shutoff is, then warm the frozen stretch slowly with a hair dryer, an electric heating pad, towels soaked in hot water, or a space heater kept clear of anything that can burn. Start near the faucet and work back. Keep going until full water pressure returns.
Will a frozen pipe burst when it thaws?
It may. The pipe splits while it’s frozen, but the leak usually shows only when the ice melts. Fairfax County Fire and Rescue says in most cases the break doesn’t appear until the water begins to thaw. Stay close to the shutoff while it thaws.
How long does it take for frozen pipes to thaw?
It depends on how cold it got and where the ice is, and no reliable source gives a set time. Our rule of thumb: if gentle heat on the pipe you can reach brings no water after half an hour or so, you’re likely heating the wrong spot or the ice is inside a wall, so call a plumber.
Can I use a torch on a frozen pipe?
No. Fairfax County Fire and Rescue says a torch thaws the water too fast and weakens the pipe until it breaks, and the Red Cross and Loudoun Water both say never to use an open flame. That includes kerosene and propane heaters.
Should I leave the faucet open when pipes are frozen?
Yes. The Red Cross says to keep the faucet open, because running water helps melt the ice as it starts to flow. It also gives the melting water somewhere to go.
Should I turn off the water if a pipe is frozen?
Know where the shutoff is either way. Fairfax County Fire and Rescue says to shut off the valve to that pipe before thawing. If the frozen spot is inside a wall or ceiling, close the main first. If it’s an exposed pipe you can watch, keep someone at the shutoff while it thaws.
How do I know if my pipes are frozen?
In freezing weather, a faucet that gives only a trickle or nothing at all, while others work, points to a frozen pipe. Check pipes on outside walls, in crawl spaces, garages and sink cabinets, and where the water line enters through the foundation.
Will frozen pipes thaw on their own?
Yes, once the weather warms or the house heats up. The risk is that it happens when nobody is watching, and if the pipe split, the leak runs until someone finds it. Thawing it while you stand by the shutoff is the safer way.
Who do I call if my water meter is frozen?
Your water utility, because the meter is theirs. Loudoun Water asks customers to call them about a frozen meter and not to open the meter box. The pipes on your side of the meter are a plumber’s job.
Frozen pipe that won’t thaw, or thawed and leaking?
Close the main shutoff if there’s any water where it shouldn’t be, then call (703) 997-9757 or use the form at the top of this page. Our plumbing diagnosis visit is $49 during regular hours and $250 after hours, and if it can wait, you can book online.
SwiftPro Heating, Cooling & Plumbing repairs and replaces water lines, water heaters, drains and fixtures across Northern Virginia from three locations in Chantilly and Ashburn, with a separate plumbing team and a dedicated HVAC team. Family owned, BBB Accredited with an A rating, 24/7 emergency service, Virginia Class A contractor license 2705192276, and rated 5.0 stars across 1,138 reviews on Google, Angi, Yelp, the BBB and Facebook. Read the reviews, or see everything we do on the plumbing page.
