Knowing how to keep pipes from freezing comes down to three things: keeping warm air on the pipe, keeping water moving through it, and knowing where your shutoff valve is before you ever need it. That is the whole playbook, and every homeowner in Montgomery County can run it in an afternoon.
We say that because we spend every January on the other side of it. When a hard freeze settles over Clarksburg, the calls do not trickle in. They arrive all at once, from people who did nothing wrong except not know that the pipe running through their garage wall was one cold night away from splitting.
The gap most homeowners have is not effort. It is timing. Insulation and a dripping faucet only help if they are in place before the temperature drops, and by the time you notice a problem, the pipe has usually already cracked. So this guide is built the way we would walk you through it standing in your basement: what to do now, what to do when the forecast turns, and exactly what to do in the first ten minutes if something goes wrong.
At what temperature do pipes freeze?
Water freezes at 32°F, but a pipe inside your home does not fail at 32°F. The number that matters for most houses is around 20°F, because that is roughly where outdoor cold overwhelms whatever warmth is reaching pipes in unheated spaces.
That is a threshold, not a promise. A pipe in a well insulated interior wall can hold up through single digits. A pipe in a drafty crawl space with wind blowing across a foundation vent can freeze at 25°F. Wind exposure, insulation, and how long the cold lasts all matter more than the number on your thermostat.
How long does it take for pipes to freeze?
Six to eight hours of sustained cold below roughly 20°F is enough to freeze an exposed, unprotected pipe. That is why overnight is when it happens. The house goes quiet, nobody runs water, the temperature bottoms out around 4 or 5 a.m., and the pipe sits still in the cold for hours with nothing moving through it.
It also explains the most common call we get: everything worked fine at bedtime, and there is no water at the kitchen sink in the morning.
Why Montgomery County winters are harder on pipes than the number suggests
Our winters are not the coldest in the country. They are something arguably worse for plumbing, which is unstable. We get a stretch of 50°F days, then an overnight plunge into the teens, then a thaw. Freeze, thaw, repeat. Pipes and fittings expand and contract through every cycle, and that repeated movement is what finds the weak spot.
The local water system tells the story better than we can. WSSC Water crews repair close to 1,800 water main breaks and leaks in a typical year across Montgomery and Prince George’s counties, and during the January 2026 cold snap they logged 360 breaks and leaks in the first month alone, enough that they asked all 1.9 million customers to limit water use (WSSC Water). Those are utility mains under the street, not the pipes in your house. But the same cold that cracks a main under Route 355 is working on the pipe in your crawl space, and nobody is dispatching a crew for that one.
There is a second local wrinkle, and it depends on when your house was built:
- Older homes in Rockville, North Bethesda, and Bethesda often still have galvanized steel or early copper. Galvanized corrodes from the inside, so the wall is thinner than it looks and it has less margin when ice starts pushing outward.
- Gaithersburg and Germantown homes from the polybutylene era carry fittings that were never forgiving to begin with. Freeze stress tends to show up at the joint, not the middle of the run.
- Copper anywhere on the WSSC system is prone to pinhole leaks, and local water chemistry contributes to it. A pipe already thinned by a developing pinhole is a pipe that splits early.
- Newer construction in Clarksburg, Damascus, and Urbana usually has PEX, which handles a freeze far better than copper because it can expand slightly instead of splitting. Better does not mean immune. The brass fittings at each end still fail, and so do the valves.
If you do not know what you have, that is fine. It is one of the first things we check on a winterization visit, because it changes what we recommend.
Which pipes in your home are actually at risk
You do not need to protect every pipe in the house. You need to protect the ones that live outside your heated envelope. Walk your home and look for:
- Pipes in an unheated basement or crawl space, especially near foundation vents or a rim joist
- Anything running through the garage, including the wall shared with the house
- Exterior wall runs, most often behind kitchen sinks and in bathrooms on the cold side of the house
- Outdoor hose bibs and irrigation lines, the single most common freeze point we see
- Attic runs, which show up in some additions and bonus rooms
- Well pump lines and pressure tanks in an unheated utility space, common on properties out past Damascus and Poolesville
Two or three spots usually account for the entire risk in a given house. Find yours and you have solved most of the problem.
How to keep pipes from freezing: our winter checklist
Before the first hard freeze
Do these once, in the fall, and they carry you through the season.
- Disconnect and drain every garden hose. A hose left attached traps water against the bib and the ice backs up into the wall. If you have shutoff valves for your outdoor spigots, close them and drain the line.
- Insulate exposed pipe with foam sleeves from any hardware store. Cover the whole run, including elbows, and tape the seams. The American Red Cross recommends pipe sleeves or UL listed heat tape for the coldest sections (American Red Cross).
- Seal the drafts, not just the pipe. Foundation vents, dryer vent gaps, garage door gaps, and the hole where a cable or hose bib passes through the wall. A pipe wrapped in foam still freezes if 15°F air is blowing directly on it.
- Blow out or shut down the irrigation system. Sprinkler backflow assemblies sit above grade and are among the first things to crack.
- Locate your main water shutoff valve and turn it. Not just find it. Actually operate it, so you know it works and you know which way it turns.
When a cold snap is in the forecast
- Hold your thermostat steady at one temperature, day and night. Setting it back overnight saves a little on the gas bill and is exactly when the pipe is most exposed. Never below 55°F, which is the minimum WSSC Water recommends for the spaces where meters and interior pipes live.
- Let one faucet drip. Cold side, on the fixture served by your most exposed pipe, at a slow steady trickle. Moving water is much harder to freeze and the open faucet relieves pressure if ice does form.
- Open cabinet doors under kitchen and bathroom sinks on exterior walls so household heat reaches the supply lines.
- Leave interior doors open to rooms you normally keep closed, so heat circulates evenly.
- Keep the garage door shut. Obvious, and still the reason for a real share of our January calls.
If you are leaving town
This is where a small freeze becomes a five figure water damage claim, because nobody is home to hear it.
- Leave the heat on, set no lower than 55°F
- Shut off the main and drain the system if you will be gone more than a few days
- Ask a neighbor to walk through daily during a cold stretch
- Know that a home with a working smart water shutoff or leak sensor is the cheapest insurance in this whole article
Find your main water shutoff before you need it
If you take one thing from this guide, take this one. When a pipe bursts, you have minutes, and a half inch supply line moving at household pressure puts out a startling amount of water.
In most Montgomery County homes, the main shutoff is inside, near where the service line enters the foundation, often within a few feet of the water meter. Basement homes: look on the front foundation wall. Slab homes: check a utility closet, the garage, or near the water heater.
Go find it today. Turn it off, turn it back on, then show everyone in the house. Write it on a note taped near the panel if that helps. There is also a curb stop out by the street, but that one takes a WSSC key and a call to their emergency line, and that is not a thing you want to be learning at 2 a.m. with water coming through the ceiling.
How to tell if a pipe is frozen
Look for these before you go hunting for a leak:
- No water, or a weak trickle, from one fixture while the rest of the house runs normally. This is the clearest sign there is.
- Frost or condensation visible on an exposed section of pipe.
- A bulge or a bowed section. Ice expanding inside a copper line will visibly distort it.
- Odd sounds when you open a tap. Gurgling, banging, or a hollow rush instead of flow.
- A sewer or drain line that suddenly runs slow in extreme cold, which points to a frozen waste line rather than a supply line.
If pressure drops across the whole house instead of one fixture, freezing may not be your problem at all. Our guide to what causes no water pressure in a Clarksburg home walks through the other likely causes, including a failing pressure regulator or a leak on the service line.
How to thaw a frozen pipe safely
Once you have found the frozen section, work in this order.
- Leave the faucet open. As the ice melts, that open tap gives the water somewhere to go and lets pressure escape. Closing it is how a thaw turns into a burst.
- Apply gentle, even heat. A hair dryer on low, a heating pad wrapped around the pipe, towels soaked in hot water, or a space heater kept well clear of anything flammable. Start at the faucet end and work back toward the cold, so meltwater has a clear path out.
- Never use an open flame. No torch, no propane or kerosene heater, no charcoal. The Red Cross is explicit about this, and for good reason. It is a fire risk, and concentrated heat on one spot of a frozen pipe can rupture it outright.
- Keep going until full pressure returns. Partial flow means there is still ice in the line.
- Then check for leaks. Look over the whole thawed run, and the fittings at both ends. A crack under ice often does not show itself until the water starts moving again.
If you cannot reach the frozen section, cannot find it, or the pipe runs inside a finished wall or under a slab, stop. That is the point to call us instead of opening drywall on a guess. Our leak detection equipment lets us pinpoint the spot without tearing up the house, which is the entire reason we own it.
What to do the moment a pipe bursts
Speed is the whole game here. Water damage scales with minutes.
- Shut off the main. First move, before anything else.
- Cut power to the affected area at the breaker if water is anywhere near outlets, fixtures, or a panel. If the panel itself is wet, do not touch it. Call the utility.
- Open the lowest faucets in the house to drain the remaining water out of the system.
- Call us. Our after hours line rings to our own office team on rotation, not an answering service and not an AI. You will get a person who can actually tell you what happens next.
- Photograph everything before cleanup begins. Your insurer will want it, and the pictures are far easier to take now than to reconstruct later.
- Start removing water with towels, a wet vac, and fans. Standing water becomes a mold problem within about 48 hours.
When to call a licensed plumber
Prevention is homeowner work. Foam sleeves, a dripping faucet, a disconnected hose. You do not need us for that, and we would rather you never have to call.
Call a licensed plumber when:
- A pipe has burst, or you find a crack after thawing one
- The frozen pipe is inside a wall, under a slab, or otherwise out of reach
- Multiple fixtures have lost water at once, which points at the main line
- You have thawed the same pipe more than one winter and want it rerouted or properly insulated
- You want the house walked before winter to find the vulnerable runs while it is still 60°F outside
A note on what we can and cannot promise: our repairs carry a 90 day warranty and full replacements above ground carry one year, with longer coverage on underground water and sewer work. We will not tell you a repair is guaranteed against another freeze, because we cannot control what the weather does to the rest of your plumbing. What we will do is tell you honestly which pipes are still at risk and what it would cost to fix them.
When a freeze does take out a section of line, we handle the permits and inspections ourselves, and we work in the WSSC system every week, so you are not the one calling the county to figure out who is allowed to shut the water off. If it is an emergency, our 24/7 emergency plumbing team is genuinely staffed around the clock.
Frequently Asked Questions
At what temperature do pipes freeze?
Around 20°F for most homes, though water itself freezes at 32°F. The difference is insulation and airflow. A pipe in a heated interior wall can survive single digits, while a pipe in a windy crawl space can freeze in the mid twenties. Sustained cold matters more than a brief dip.
How long does it take for pipes to freeze?
Roughly six to eight hours of sustained cold below about 20°F for an exposed, unprotected pipe. That is why most freezes happen overnight, when nobody is running water and outdoor temperatures hit their low point in the early morning hours.
Can a frozen pipe thaw on its own?
Yes, and that is exactly the risk. A pipe that cracked while frozen holds together as long as the ice is plugging it. When it thaws unsupervised, water pours through the crack with nobody there to shut off the main. If you know a pipe is frozen, thaw it deliberately and inspect it afterward.
Do frozen pipes always burst?
No. Plenty of pipes freeze, block flow for a few hours, thaw out, and are perfectly fine. Bursting depends on where the ice forms, how much pressure builds behind it, and the condition of the pipe. Older galvanized and thinning copper are far more likely to split than newer PEX.
Does homeowners insurance cover frozen pipes?
Sudden water damage from a burst pipe is typically covered, but policies commonly exclude damage tied to negligence, such as leaving the heat off in an unoccupied home. Coverage varies, so read your policy or ask your agent. To be clear about our role: we do not act on your behalf with your insurer. We will gladly answer their questions about the work once the repair is paid.
How much does it cost to fix a frozen or burst pipe?
It depends almost entirely on access. A cracked hose bib or an exposed basement line is a straightforward repair. A pipe inside a finished wall, under a slab, or on the buried service line runs considerably higher, and underground work on our side ranges from about $1,500 to well over $20,000 depending on depth, rock, and obstacles. We give free estimates and we will show you the range before we start.
Should I leave the faucet dripping all night?
During a hard freeze, yes. A slow steady drip on the cold side of the most exposed fixture keeps water moving and relieves pressure if ice starts to form. The water it uses over one cold night costs a tiny fraction of a single burst pipe repair.
Do PEX pipes freeze?
PEX can freeze, but it tolerates it much better than copper because it expands slightly instead of splitting. The vulnerable points are the brass fittings and valves at each end. If your Clarksburg or Urbana home was built in the last twenty years, you likely have PEX, and you still want the exposed runs insulated.
The short version
Insulate what is exposed, hold your thermostat steady, let one faucet drip when it gets cold, and know where your main shutoff is. Those four habits prevent the overwhelming majority of the frozen pipe calls we take every winter.
The ones that get expensive are almost always the ones nobody caught in time. So if you are not sure which pipes in your home are exposed, ask us in October rather than in January.
Have a frozen pipe right now, or want a hand getting your home winter-ready? Book online or call us anytime at (301) 972 2223.
