Keeping pipes from freezing during a Maryland cold snap
Maryland does not get the long, deep cold of northern New England, and that is part of the problem. A house that sees a few light freezes a winter gets a three-night stretch in the teens and the weakest pipe in the building finds out about it. Most of the burst pipes we hear about come from a short list of spots, and most of them could have been protected in an afternoon.
Which pipes go first
Cold gets into a house through the places where the building envelope is thin. Look for supply lines in these spots before the forecast turns.
- Kitchen and bathroom sinks on an outside wall, where the pipe sits close to the cold sheathing.
- Lines in the crawlspace or running across the underside of a floor over an unheated space.
- Outdoor hose bibs, and the stub of pipe behind the wall that feeds them.
- Pipes along the rim joist, the band of framing that sits on top of the foundation, where air leaks are common.
- Garage, attic and porch lines, and any supply that passes near a dryer vent or an opening in the wall.
A useful rule of thumb is that trouble starts when temperatures stay near or below 20°F for several hours. Wind makes it worse, and so does a gap that lets outside air sweep across a pipe.
A timeline for the 48 hours before a hard freeze
| When | What to do | Why it helps |
|---|---|---|
| Two days out | Disconnect garden hoses. Shut the interior valve to each hose bib and open the outdoor spigot to drain it. | Water left in the stub freezes and splits the pipe behind the wall. |
| Two days out | Find your main water shutoff. Make sure everyone in the house can turn it. | In a burst, the first minute decides how much water you get. |
| One day out | Add insulation sleeves to exposed pipes in the crawlspace, garage and basement. Seal gaps where lines enter the house with caulk or spray foam. | Insulation slows heat loss. Sealing stops moving air. |
| One day out | Plan to leave the thermostat steady. Do not set it back much at night. | A big overnight drop gives the pipes less warmth when it matters. |
| Night of the freeze | Open cabinet doors under sinks on outside walls. Let a faucet drip, cold and hot, on the lines most at risk. | Room air reaches the pipe. Moving water is harder to freeze. |
| Day after | Look at the lines, the ceilings and the crawlspace for wet spots as things warm up. | Breaks often show up when ice that was blocking a pipe thaws. |
Why dripping a faucet helps
People think a drip works because moving water cannot freeze. That is partly true. The more useful effect is on pressure. When ice forms a plug in a line, the water between the plug and a closed faucet has nowhere to go, and pressure builds until the pipe splits at its weakest point. An open faucet gives that water an exit. A thin stream is enough, and it costs a little on the water bill compared with a flooded basement.
Drip the faucet that is farthest from where the line enters the house, and choose the ones on the exposed lines first.
If you are leaving town
An empty house has no one to hear water running. If you will be away in cold weather, keep the heat on, ideally no lower than the mid-fifties, and ask someone to look in. If you are gone for more than a few days, shutting off the main and draining the lines is the safest route, though that is a bigger job and it affects fire sprinklers and some heating systems, so ask a plumber first if you have either.
Found water after a freeze?
Close the main valve, then call. Pumping can begin while you wait for a plumber.
Call (301) 786-0888What not to do
- Do not use a torch or open flame to thaw a pipe. It starts fires and can split the pipe.
- Do not leave a space heater running unattended near wet or flammable materials.
- Do not use heat tape that is not made for your type of pipe, and do not wrap it over itself. Follow the instructions on the package.
- Do not turn the heat up high all at once on a frozen line. Slow warming is safer.
- Do not ignore a trickle. A faucet that runs slowly in the morning may be a line that is frozen and about to move.
If a pipe does freeze
If a faucet gives only a trickle or nothing in cold weather, a line is probably frozen. Open the faucet so the water has a path as the ice melts, then warm the pipe slowly with a hair dryer or a towel soaked in warm water, starting at the faucet end and working back toward the frozen part. If you see water, a crack or a bulge, stop, shut off the main and call. A split line that thaws starts to flow immediately.
If water is already running, the sequence of cleanup work is covered on our frozen and burst pipe cleanup page and in the post on the first hour after a pipe bursts. The first priority is always the same: get the water stopped, then get what is standing out of the house with emergency water extraction.
A note on older houses
Houses from the 1960s and 1970s often have lines in exterior walls and crawlspaces that were never insulated to today's standard. That is the first place to look. Our page for West Laurel talks about the age of the homes there and what tends to fail in them. If you are not sure where your lines run, a plumber can trace them and tell you which ones are exposed.
Where this leads if a pipe does freeze
- Frozen & Burst Pipe Cleanup What happens after a freeze breaks a line.
- Emergency Water Extraction Pumping out standing water first.
- Water Damage Restoration The whole process from stopping the source to drying.
Local note: see our page for West Laurel. It covers the age of the homes and what wears out first.
Keep reading
- October 14, 2026The first hour after a pipe bursts: what to do and what to avoid
- November 2, 2026Ice dams and ceiling leaks in Maryland winters