So you researched and read about all the things you should do to prep your home for winter, and maybe you had the best intentions of taking care of most if not all of those things before the cold arrived. But maybe - for whatever reason(s) - you never got around to them.
Now here we are, on the verge of winter's "official" arrival and in the midst of a pretty darn cold spell. If one of those things you never got to was insulating your water pipes, there are things you can do to minimize the possibility of having them freeze and cause major damage to your home.
If you're planning to be away from home, shut off the water supply and drain the system of any residual water. No water in the pipes means they can't freeze. You should also consider draining your hot water heater and/or boiler. You should also keep your thermostat set no lower than 55 °F and ask a friend or neighbor to check daily to make sure your home is warm enough to prevent freezing.
However, you're going to be home for most of the winter, so what else can you do?
One trick is to let all your faucets drip warm water overnight. This keeps the water moving in the pipes, and moving water doesn't freeze as easily as standing water. And if freezing does still occur, those dripping faucets will relieve any pressure built up between the freeze and the faucet. This pressure buildup is what causes pipes to burst.
Because pipes that are located along exterior walls, in under-sink cabinets or in closets are most likely to freeze, leave cabinet or closet doors open to allow warm air to circulate around them. You should also seal or block off any cracks or holes in those exterior walls because when severe cold weather hits, even a small opening can let in enough air to cause pipes to freeze. The most common sources are around wiring, dryer vents and pipes. These can usually be sealed with caulking or insulation.
If you have exposed pipes, particularly along exterior walls, should be wrapped or insulated in some way. Ideally, you should use building insulation, but if that's not possible, there are other materials, such as heat tape, that will work. This is something you should be able to do yourself. If you're not quite sure how to go about it, DIY Network has a great how-to here. One important thing to remember is that the more insulation you can use, the better your pipes will be protected.
For homes that have a crawlspace, be sure to close all air vents located on the foundation wall to help protect the pipes located in that area.
If you haven't already, unscrew all hoses and shut off the water supply to outdoor faucets - and do it now.
If your pipes do end up freezing, all is not lost. Turn on your faucets, and if nothing comes out, leave them turned on and call a plumber. If your pipes have already burst, locate the main shutoff valve to your house and turn it off.
You may be able to thaw a frozen pipe using a hair dryer. Start warming the pipe close to the faucet, then work your way back to its coldest section.
One last piece of advice: Never try to thaw a pipe with a torch or other open flame for obvious reasons. Water damage from a burst pipe is nothing compared with burning your house to the ground.