How To Thaw a Frozen Pipe

Years ago my ex-husband and I lived on a houseboat. Because our water pipe ran along a dock, we had to keep an eye on the pipe in the winter.....if it got too cold, we would shut the water off at shore and empty the water in the pipe so as to prevent it from freezing. On borderline cold days, we would leave the faucets in the houseboat on in a slow drip to prevent the water from freezing. But every once in a while, if we didn't shut the water off in time and forgot to leave the faucets dripping, the water in the pipe would begin to freeze.

One time the water pipe had just begun to freeze and my husband and I stood on the dock debating how best to thaw it. I suggested wrapping the pipes with towels soaked in hot water while he recommended a blowtorch. As this was in the days before the Internet (I told you it was long ago!), we couldn't simply resolve the disagreement via a quick search. I suggested that while he ask around for a blowtorch, I would try the hot towel method. Fortunately, the towels ended up thawing the pipe just fine, minus any conflagration. If you've got a blowtorch-bearing hubby at hand, read on for some other pipe-thawing tips:

  1. Pipes likely to freeze. The pipes that are most likely to freeze are those most exposed to the cold--like water pipes in unheated interior spaces such as attics, garages or crawl spaces, pipes that run along exterior walls or even pipes in bathroom or kitchen cabinets. Your best bet is to insulate these pipes well and avoid the issue altogether (but you already know that).
  2. How to tell if your pipe is frozen. If, when you turn your faucet on, only a trickle of water comes out, chances are good that your pipe is frozen. Though it may be counterintuitive, leave your faucet on. This is because as you begin to melt the frozen area of pipe, water will begin to flow. Open the other faucets in the house. If water flows through them freely, you can shut them off, but if you get only a trickle, leave both the hot and cold water faucets on.
  3. Turn off your water main. This will limit any flooding that could occur from a pipe that may already be broken. It will also prevent gushing when you thaw the pipe.
  4. Locate the pipe that is frozen. In short, you're looking for any pipe that is not insulated. Good places to look are where the water pipe enters the home, along foundation walls or next to exterior walls, particularly under kitchen or bathroom sinks. If you find a spot where the pipe passes through an area without insulation, apply heat there. Work in the direction from the faucet toward the frozen pipe.
  5. Slowly thaw the pipe. Use either an electric heating pad, a blowdryer, a space heater, or towels soaked in hot water. If using electrical appliances, be sure that the outlet you plug them into is grounded (ideally, the outlet should be a ground fault interrupt protected outlet).
  6. Turn the water main back on. Let the water run for a minute or two.

Turns out that a blowtorch (or any other device with an open flame) can actually cause the water in a frozen pipe to boil and explode! So save the blowtorch for your creme brulee.


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