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Rockland County winters regularly bring nights in the single digits, and that is cold enough to freeze a water pipe in an outside wall, a crawl space or an unheated garage. The ice itself does not split the pipe. The pressure that builds between the ice and a closed tap does. That is why a frozen pipe often shows itself only when it thaws and starts to spray.
How to tell
You open a tap on a very cold morning and get a trickle, or nothing, while other taps work normally. You may see frost on an exposed pipe, or a slight bulge.
Before you thaw anything
- Find your main shut-off valve and make sure you can close it quickly. If the pipe has already split, it will leak as soon as the ice melts.
- Open the affected tap, both hot and cold. Moving water helps melt the ice, and the open tap releases pressure.
- Look along the pipe for cracks or bulges. If you find one, close the main valve now and call a plumber.
Thawing the pipe
Start at the end nearest the tap and work back toward the frozen section, so that melted water has somewhere to go.
Safe sources of heat:
- A hair dryer, kept moving along the pipe
- A heating pad wrapped around it
- Towels soaked in hot water, replaced as they cool
- A small space heater aimed at the area from a safe distance, never left unattended
- Turning up the heat, and opening cabinet doors and the door to the basement
Never use a blowtorch, a propane heater, a heat gun on plastic pipe, or any open flame. Every winter, house fires are started by people thawing pipes with a torch. A flame can also boil the water inside the pipe and burst it.
Keep going until the tap runs at full pressure. Then check the whole length of the pipe for leaks over the next hour.
When to call a plumber
- You cannot find the frozen section, or it is inside a wall
- The pipe has cracked or is bulging
- Several taps are affected, which can mean the main supply line has frozen
- You have no water anywhere in the house
Stopping it from happening again
Before winter:
- Disconnect garden hoses. Close the inside valve to each outdoor faucet, then open the faucet outside to drain it.
- Put foam pipe insulation on any pipe in a crawl space, garage, attic or along an outside wall. It is cheap and takes minutes to fit.
- For a pipe that freezes every year, thermostatic heat cable is a dependable fix. Follow the maker's instructions exactly.
- Seal the gaps where pipes and cables pass through outside walls. A draft of freezing air does more harm than low temperature alone.
On the coldest nights:
- Leave the taps on vulnerable pipes running at a thin trickle, hot and cold
- Open the cabinet doors under sinks on outside walls
- Keep the garage door shut
- Keep the thermostat at the same setting overnight
If you are going away: leave the heat on, at no lower than 55°F, and ask someone to look in on the house. For a long absence, a plumber can drain the system.
If a pipe bursts
Close the main valve, open the taps to drain the pipes, keep clear of any water near electrics, photograph the damage, and find a licensed plumber.