Frozen pipes can be a nuisance when they prevent you from accessing your water supply. If the pipes freeze enough to split them, they can be more than a nuisance by flooding your house and causing major water damage. If you live in a climate that gets cold enough to burst pipes, you need to take steps to prevent this from happening.
Your pipes won't freeze unless the outside temperature is below freezing. Even then, if your house is properly built and insulated, it is very unlikely that your pipes will freeze. The only time you need to leave the water running to prevent the pipes from freezing is during extremely cold weather that is cold enough to get through your insulation and drop the temperature around your water pipes below freezing. When you leave the water running, a very tiny stream is sufficient to prevent freezing. As long as the water is moving, it will not freeze.
If you fear that your pipes are in danger of freezing, there are several other things you can do. Open the cabinet doors in your kitchen and bathrooms to allow the warmer house air to more easily get to where the pipes are. Turn the heat up in your house. During the day when you are around, you don't need to leave the water running, just turn your faucets on for a moment every hour or so. This will move the water and discourage any freezing that might have started.
If your pipes do freeze, you should thaw them as quickly as possible to prevent them from freezing even more. In most cases when water freezes in a pipe, it won't burst the pipe if you thaw it in time. If you allow it to freeze to a point where it splits the pipe, you will graduate from a nuisance into a genuine and expensive problem. The easiest way to thaw a pipe is with a hair dryer. Determine where the most likely point of freezing is and direct the hot air from the hair dryer directly onto the pipe. Leave the taps open and wait for water to begin coming through them.
When you leave water running at night, use the tap that is farthest from where the main water pipe enters your house. This will keep water moving throughout the system. Be sure that you know where the main water shutoff is. If your pipes burst, you need to be able to turn off the water supply to minimize the amount of damage.If you have a recurring problem in the same place every year, install heavier insulation between this part of the pipe and the outside.