TheTradesmanShopHow to Keep Your Pipes From Freezing (and What to Do If They Do)
A hard freeze is coming and your pipes are the most expensive thing in your house that water can ruin. A burst pipe at 2 AM will do more damage in an hour than a whole winter of heating bills. Here is what actually works, in the order that matters.
1. Drip the faucets on exterior walls
Moving water is much harder to freeze than still water. Pick the faucets served by pipes in exterior walls, especially on the side of the house that gets the wind, and let them run in a stream about as thick as a pencil lead. Not a drip. A thin, steady stream. Yes, it costs a little water. A burst pipe costs thousands. Do the math.
2. Open the cabinet doors
The pipes under your kitchen and bathroom sinks sit in cold little boxes with the doors shut. Open the cabinet doors so the heat from the house can reach them. If you have kids or pets that get into cleaners, move the cleaners first, then open the doors. This one is free and people skip it every year.
3. Find your main water shutoff TODAY
Not when water is spraying. Today. It is usually where the water line enters the house: basement wall, crawlspace, garage, or a utility closet. Turn it and make sure it actually turns, because old gate valves seize up from never being touched. If yours will not budge, that is a plumber call on a calm weekday, not an emergency call at midnight. Tag it with a bright ribbon so anyone in the house can find it.
4. When a pipe freezes
You will know: a faucet gives you nothing, or just a trickle. First, leave that faucet open. As the ice melts, water needs somewhere to go, and pressure against a closed faucet is what bursts pipes. Then warm the pipe gently. A hair dryer works. Warm towels soaked in hot water work. A space heater aimed at the area works if you keep it a safe distance. Work from the faucet back toward the frozen section so melting water can escape.
What you do NOT do: never use a torch, a heat gun on high, or any open flame. You will start a fire inside your wall, and I have seen the aftermath. Patience beats a torch every time.
5. The burst drill
If a pipe lets go, you have minutes before the damage spreads. One: shut the main off. Two: kill power to the affected area at the breaker if water is anywhere near outlets, switches, or the electrical panel. Water and electricity do not negotiate. Three: open the lowest faucet in the house to drain what is left in the lines. Then call a plumber and your insurance company, in that order, and take photos of everything before you start cleaning up.
Quick answers
At what temperature do pipes start to freeze?
Twenty degrees Fahrenheit is the real danger line, especially if it stays there overnight. Pipes in crawlspaces, attics, garages, and exterior walls go first because they get the least heat from the house. Wind makes it worse. If the forecast says low twenties or teens, do the drip and cabinet routine that night.
Should I drip hot water, cold water, or both?
Cold is the one that matters most, since cold lines freeze first. But if your hot water pipes also run through cold spaces, let both run a thin stream. The cost of the water is nothing next to a burst pipe. When in doubt, drip both.
If my pipe froze but did not burst, am I in the clear?
Mostly, but check it. Once it thaws, look and listen for drips, hissing inside walls, or water stains on ceilings and drywall over the next day or two. A pinhole crack from the freeze can leak slowly. If your water bill jumps next month for no reason, you missed one.