How do I know if my pipes are frozen?
The surest sign is a faucet that gives you nothing, or only a trickle, on a very cold morning while other faucets still run. Other signs:
- Frost on an exposed pipe in a crawlspace, garage or basement
- A section of pipe that looks bulged
- A toilet that will not refill
- No water at a faucet on an outside wall, like a kitchen sink against the north side of the house
If no faucet in the house runs, the freeze may be near where the water line enters the house, or the problem may be outside your home. Fairfax Water and Loudoun Water customers can contact their utility to check for a service problem.
What to do if your pipes freeze: step by step
- Check for a break first. Look along the pipe for a crack, a bulge or water. If you find any, shut off the main water valve before you thaw anything. A cracked pipe leaks the moment it thaws.
- Open the faucet. Open the faucet the frozen pipe feeds, both hot and cold. Melting water needs somewhere to go, and running water helps melt the rest of the ice.
- Find the frozen section. Follow the pipe from the faucet back toward where it runs through a cold space: an exterior wall, a crawlspace, the garage, or under a cabinet against an outside wall.
- Apply gentle heat. Use a hair dryer, an electric heating pad, or towels soaked in hot water. Start near the faucet and work back toward the frozen spot. Keep the hair dryer away from standing water.
- Keep going until full pressure returns. Then check every other faucet in the house. If one pipe froze, others may have too.
- Watch for leaks for a few hours. Check under sinks, ceilings below bathrooms, and the basement.
If you cannot reach the frozen section, or it is inside a finished wall, call a licensed plumber. Do not cut into a wall to get to it.
At what temperature do pipes freeze?
Water freezes at 32 degrees Fahrenheit, but a pipe inside a home is usually protected by the house around it. State Farm and the Red Cross treat outdoor temperatures below about 20 degrees as the point where pipes in uninsulated spaces are most at risk. Pipes hit by cold drafts or wind can still freeze above 20.
| Outdoor temperature | What happens | Risk |
|---|---|---|
| Above 32°F | Pipes do not freeze | None for pipes |
| 32°F to about 20°F | Exposed pipes in unheated spots can freeze, especially with wind | Moderate |
| Below about 20°F | Pipes in crawlspaces, garages, attics and outside walls are at real risk | High |
| Multi-day stretch in the teens or lower | Risk spreads to pipes that rarely freeze | Very high |
Northern Virginia winters are mild most of the time, so many homes have pipes in places that never see a long freeze. A few nights in the teens is when the calls start.
How long does it take for pipes to freeze?
There is no single number. It depends on how cold it gets, how long it stays cold, how well the pipe is insulated, and how much wind blows on it through gaps in the wall or foundation.
- Fastest: uninsulated pipes in crawlspaces, unheated garages, attics and outdoor spigots during a windy cold snap. These can freeze overnight.
- Slower: pipes in exterior walls behind kitchen and bath cabinets, especially if the doors are closed and the heat is turned down.
- Rarely: pipes in interior walls of a heated home.
Which pipes freeze first in Northern Virginia homes?
The ones that run through spaces the furnace does not heat. In the split-levels, ramblers and colonials common across Fairfax and Loudoun counties, these are the usual suspects:
- Crawlspace lines. Many older homes have supply lines running under the floor in a vented crawlspace. Open vents let freezing air sit around the pipes all night.
- Kitchen sinks on outside walls. The supply lines sit in the exterior wall behind a closed cabinet, so warm room air never reaches them.
- Rooms over the garage. A bathroom or laundry above an unheated garage often has pipes in the garage ceiling.
- Outdoor spigots. A hose left connected traps water in the fitting and the pipe behind it.
- Basement bathrooms and bars. Lines that run along a foundation wall or through a cold rim joist area.
- Townhome and condo walls. A pipe in a shared wall can freeze if the unit next door is empty with the heat turned down.
Should I call a plumber or a restoration company?
Call a plumber to thaw a pipe you cannot reach or to repair the break. Call a restoration company when water has gotten into the house. Often you need both, and the sooner the water comes out, the less has to be torn out.
- Frozen, no leak: thaw it yourself if you can reach it, or call a plumber.
- Cracked pipe, little water: shut off the water and call a plumber. Check the wall and ceiling below for wet spots over the next day.
- Water on floors, through ceilings or in walls: shut off the water and call us for extraction and drying, and have the pipe repaired.
What happens when pipes freeze?
Water expands as it freezes. In a closed pipe, that builds pressure between the ice and the nearest closed faucet until the pipe or a fitting splits. Ice often plugs the crack while it is cold, which is why the leak usually starts when the pipe thaws, hours or a day after the coldest night.
Will PEX pipe freeze and burst?
Yes, it can. PEX tends to handle a freeze better than copper because the tubing can stretch slightly, but it is not freeze-proof. Repeated freezes, extreme cold, and fittings and connections, which do not stretch, are where PEX systems commonly fail. Copper has less give and tends to split after a hard freeze.
| Pipe | Freeze behavior |
|---|---|
| PEX | More forgiving, but can still split. Fittings are a weak point. |
| Copper | Little give. Splits are common after a hard freeze. |
What if the frozen pipe bursts?
Act fast. Water comes out at full house pressure once the ice melts, and it spreads through drywall, insulation and subfloor quickly.
- Shut off the main water valve.
- Stay out of rooms where water is near outlets, cords or the electrical panel, or a ceiling sags.
- Take photos and video before you move anything. Your insurer will want them.
- Call us. We extract the water, dry the house until moisture readings say dry, document it for your insurer and rebuild with the same crew. Burst pipe cleanup and repair
Water coming through a ceiling below a bathroom? See Water leaking from the ceiling: what to do. Wondering about coverage? Read Does homeowners insurance cover burst pipes?. For what happens during the dry-out, see What is water mitigation?.
How do I keep it from happening again?
Once the pipe is thawed or fixed, the next freeze is the one to plan for. Insulate exposed pipes, seal drafts, drip faucets on the coldest nights and keep the heat steady. The full checklist is in How to prevent frozen pipes in Northern Virginia. If you are not sure who to call when something goes wrong, see Who to call for water damage.