Drip faucets in freezing weather to prevent pipe burst

Aug 13, 2023

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Fall is quickly turning into winter, and temperatures across much of the U.S. reflect it.

Along with winter comes cold weather problems like frozen pipes.

"Not only can frozen pipes prevent water from flowing properly, but they can potentially burst and cause flooding to your home," Nationwide Insurance says.

Over the past year, many people have gone to Google to look up how to prevent frozen pipes. Some advice online says the answer is to just let your faucets drip.

Can leaving faucets dripping prevent pipes from bursting in freezing weather?

American Red Cross

Christoph Lohr, vice president of technical services and research for the International Association of Plumbing and Mechanical Officials (IAPMO)

University of Illinois Building Research Council

Mississippi State University

J. Blanton Plumbing, a plumbing company based in Illinois

Millwood Plumbing, a plumbing company based in Georgia

Yes, leaving faucets dripping can prevent pipes from bursting. The water dripping from the faucet should be cold, since it's more likely to freeze than warm water.

If there are freezing temperatures outside, the American Red Cross says you should let cold water drip from faucets. Water running through your pipes, even at a slow trickle, can help prevent them from freezing, the Red Cross says.

Water expands when it freezes. If the water inside of a pipe freezes, it can block part or all of the flow of water within the pipe, causing the pressure to increase, which in turn could cause the pipe to burst.

Standing water freezes more quickly than running water, say Chicago area J. Blanton Plumbing and Georgia-based Millwood Plumbing. So when you set your faucets to a drip, the water in your pipes begin to move just enough to keep it from freezing as easily as it would when turned off.

Even when your taps are off, water remains in your pipes — that's how you have instant water when you turn any of them on, and also why it sometimes takes awhile for hot water to warm up after you turn a tap on.

Christoph Lohr, vice president of technical services and research for the International Association of Plumbing and Mechanical Officials (IAPMO), explained in an email to VERIFY that the pipes supplying your home with water are always filled with standing water.

"When you shut off the faucet, the water that is still being pushed by the pumps back at the water treatment plant will fill the entire pipe up to your faucet," Lohr said. "Water expands as it freezes, so the water that is filled in your pipe as it freezes will increase in volume until it causes the pipe to burst."

The University of Illinois Building Research Council says a "typical freezing event" in home water pipes happens at around 20 degrees Fahrenheit. But to be on the safe side, you should consider dripping your faucets if temperatures are below freezing — 32 degrees Fahrenheit or less. Mississippi State University recommends that you continue to leave your faucets dripping until the temperature is consistently above freezing once again, just to be on the safe side.

You should allow cold water to drip rather than warm water, since your cold water supply is far more likely to freeze than your hot water supply. Additionally, if you know the location of the faucet farthest from your main water supply, you should drip that one. That faucet will get water moving all the way through your home, allowing you to limit the faucets you drip to just the one, according to Mississippi State University. Faucets connected to pipes along exterior walls and uninsulated areas, such as an attic, should also be priorities for dripping.

And you don't have to run much water for dripping to be effective. Mississippi State University says you can drip the water at a rate of one drop every few seconds.

How else can you prevent frozen pipes? The Red Cross recommends closing off valves supplying water to outdoor spigots, and then draining those spigots. Insulating your pipes helps, as does insulating the areas of your home where pipes are located. Finally, opening up cabinet doors beneath your kitchen and bathroom sinks can help — that allows some more heat from the room to get to the pipes hidden within those cabinets.

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