Why pipes burst
The American Red Cross explains it simply: water expands as it freezes, and that expansion puts tremendous pressure on whatever is containing it, including metal or plastic pipes. No matter the strength of the container, expanding water can cause pipes to break.
The Red Cross lists the pipes that freeze most often: pipes exposed to severe cold such as outdoor hose bibs, swimming pool supply lines and sprinkler lines; supply pipes in unheated interior areas like crawl spaces, attics, garages and kitchen cabinets; and pipes that run against exterior walls with little or no insulation. If your home has a crawl space, it belongs on that list.
Before the cold arrives
The Red Cross recommends draining pool and sprinkler supply lines following the manufacturer's directions, without adding antifreeze unless directed. Remove, drain and store outdoor hoses. Close the inside valves that supply outdoor hose bibs, then open the outside bibs so any remaining water can expand without breaking the pipe.
Add insulation to attics, crawl spaces and basements, and insulate both hot and cold pipes in unheated areas such as garages and under sinks. The Red Cross mentions pipe sleeves and UL-listed heat tape or heat cable for exposed pipes, and notes that even a quarter inch of newspaper can provide meaningful protection where freezing is not frequent or prolonged. If you have an irrigation system with a backflow assembly, see backflow testing for how it fits into Raleigh Water's rules.
During a cold snap
Keep garage doors closed if water lines run through the garage. Open kitchen and bathroom cabinet doors so warmer air can reach the plumbing, moving cleaning products out of children's reach. When it is very cold, the Red Cross advises letting cold water drip from faucets served by exposed pipes, because running water, even at a trickle, helps prevent freezing.
Keep the thermostat at the same temperature day and night; the Red Cross acknowledges this may raise the heating bill but says it can prevent a much more costly repair. If you will be away during cold weather, leave the heat on at no lower than 55 degrees Fahrenheit. Those drips do show up on your water bill, but the cost is small compared with a burst pipe; our calculator shows what a given flow costs at Raleigh Water's rates.
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Free Quote RequestThawing a frozen pipe safely
If you turn on a faucet and only a trickle comes out, suspect a frozen pipe, usually against an exterior wall or where the service enters through the foundation. Keep the faucet open, since running water helps melt the ice. The Red Cross says to apply heat with an electric heating pad, a hair dryer, a portable space heater kept away from flammable materials, or towels soaked in hot water, and to keep going until full pressure returns.
Do not use a blowtorch, kerosene or propane heater, charcoal stove or any other open flame. If you cannot find the frozen section, cannot reach it, or cannot thaw it, the Red Cross says to call a licensed plumber. Check every other faucet too, because if one pipe freezes, others may as well.
When a pipe has already burst
Shut off the main valve at once, then open the lowest faucet to drain the system. Turn off the water heater's supply and its power or gas if the house will be without water for a while. Follow the steps in what to do in a plumbing emergency to limit damage and document it for your insurer.
Repairs to burst supply lines are plumbing repairs, and North Carolina law requires permits for the general repair of plumbing systems, so ask the plumber whether a permit is needed; see plumbing permits in Wake Forest. Then check your next bill, as described in our high water bill guide.