A couple of winters ago, I leaned a hand against the wall in my laundry room’s back corner during a hard freeze. I flinched. The drywall was cold. Not chilly, cold, the kind that tells you the only thing between that wall and the weather is some studs and a prayer. I knew a supply line ran through there. Standing there in my socks, I got nervous about what the morning might bring.
That’s really what started me down the rabbit hole of how to prevent frozen pipes. The good news is that prevention is cheap and mostly common sense. Pipes burst because freezing water expands, pushing against trapped liquid water and building up pressure until the pipe splits. Stopping that costs a few dollars and an afternoon. Fixing a flooded house costs a great deal more.
Which Pipes Freeze First (and at What Temperature)
Not every pipe in your house is at equal risk. The ones that freeze first live in the cold, unheated corners: attics, basements, crawl spaces, garages, and especially the lines tucked inside exterior walls. Outdoor faucets and the hose bibs feeding sprinkler systems are usually first to go, since they sit right in the weather.
Uninsulated pipes running against an exterior wall carry the highest risk, because there’s so little between them and the outside air. That back corner of my laundry room is a textbook example.
Guidance generally says to act when outside air drops into the low 20s Fahrenheit. Act sooner for pipes in poorly insulated spots. Water freezes at 32, but the air has to pull the pipe itself down that low, which takes a sustained cold spell. Treat a hard freeze as your cue to act, not a single chilly night.
Cheap Steps to Prevent Frozen Pipes
Most of what works here you can grab at any hardware store for pocket change. The goal is simple: keep the vulnerable pipes warmer and keep the outdoor ones empty.
Here’s the short list I run through every fall:
- Slide foam pipe sleeves over any exposed pipes in the basement, garage, crawl space, or attic. They’re inexpensive and take minutes to install.
- Add heat tape or heat cables to the highest-risk runs, the ones you already know get cold. Follow the product instructions carefully, since these plug in and generate warmth.
- Seal drafts and gaps near pipes with caulk or spray foam. A surprising amount of cold air sneaks in through the holes where pipes pass through walls and floors.
- Disconnect and drain garden hoses before the first freeze. A hose left attached traps water right at the faucet, and that frozen plug can back up into the wall.
- If your home has interior shutoffs, shut off and drain the valve for each outdoor faucet. Then slip an insulated faucet cover over the spigot.
Inside, open the cabinet doors under sinks that sit against exterior walls. It feels almost too easy, but letting warm room air reach the pipes under there makes a real difference. If you have foil around, some people wrap it near drain pipes for a little reflected warmth. Insulation is still the dependable fix.
What to Do Before a Severe Cold Snap
When the forecast turns ugly, a few habits buy you a lot of safety. Keep the thermostat set to the same temperature day and night. You might want to drop it at bedtime to save money. But a steady setting keeps pipes inside the walls warmer through the coldest hours.
Don’t let the indoor temperature fall below about 55 degrees, even when you’re out. If you travel during a cold stretch, leave the heat on instead of shutting it down to save money. A frozen pipe erases any savings instantly.
Letting a faucet drip is the classic trick, and it works. Running water, even a trickle, resists freezing far better than still water in the pipe. Open a cold-water faucet at the fixture farthest from your main valve so water moves through the longest run. And before any of this, go find your main water shutoff and make sure you can reach it fast.
What to Do if a Pipe Freezes or Bursts
The first sign is usually a faucet that gives you nothing, or just a sad trickle, when you turn it on. Frost on the pipe itself is another dead giveaway. Trace the cold line back to the spot that feels frozen.
Keep that faucet open while you thaw, so melting water has somewhere to escape. Warm the frozen section gently. Use a hair dryer, towels soaked in hot water, or a portable space heater kept well away from anything flammable. Work from the faucet end toward the frozen spot.
A lesson I picked up through experience: do not reach for an open flame or a blowtorch. You might feel tempted when cold and impatient, but an open flame can crack the pipe or start a fire. It’s just not worth it. If a pipe has already burst, shut off the main water valve right away, then deal with the mess.
When to Call a Plumber
Call for help if you can’t find the frozen section. Also call if you can’t reach it behind a wall or ceiling, or if thawing doesn’t restore the water. And absolutely call if a pipe has split. A quick service visit is nothing compared to replacing drywall, flooring, and soaked belongings after a flood.
If you want a deeper walkthrough on the thawing side, here’s a guide on how to thaw frozen pipes safely. Before the first freeze, find your main water shutoff and label it. Then you won’t hunt for it in the dark while water pours through the ceiling.
FAQ
At What Temperature Do Pipes Freeze?
Water freezes at 32 degrees Fahrenheit, but a pipe needs a sustained cold spell to drop that low. General guidance says to start taking precautions once outside air falls into the low 20s. Take precautions earlier for pipes in uninsulated garages, attics, or exterior walls.
Should I Let My Faucets Drip All Night?
During a hard freeze, yes. A slow trickle of water keeps it moving through the pipe, which resists freezing far better than still water. Open the cold-water faucet farthest from your main valve so water travels the longest run of pipe.
Should I Leave the Heat On When I’m Away?
Yes, leave it on if you’ll be gone during cold weather. Set the thermostat no lower than about 55 degrees. The cost of running the heat is minor next to the damage a single burst pipe can cause while you’re out.
Can I Use a Space Heater to Thaw a Frozen Pipe?
A portable space heater can work for gentle thawing, as long as you keep it well away from anything flammable and never leave it unattended. A hair dryer or hot-water-soaked towels work too. Never use an open flame or blowtorch.
How Do I Know if a Pipe Is Already Frozen?
The clearest signs are no water or only a weak trickle from a faucet, and visible frost on the pipe. If one faucet runs fine and another gives you nothing on a freezing day, the line feeding the dry one is the likely culprit. Locate and label your main water shutoff before winter, so you’re ready either way.
