If you're going to be out of town for a while, shut off the water to the house and to the water heater, and drain the system. If possible blow air into the system to get all of the water out. This will prevent water freezing in the pipes, and expanding. Main thing I want to stress is: unless you are an expert – call your plumber. However, I’ve got some great ways to keep your pipes from freezing as well as what to do if they do freeze.
1. How to prevent frozen pipes
a. When first installing keep as much of the piping away from exterior walls and use properly insulate piping, with for example Thermacell/Armaflex.
b. Use special outdoors frost-free outside faucets.
c. Leave a faucet or multiple faucets at a slow drip to allow for the expansion of the water relief.
2. What if pipes freeze?
a. Locate shut off valve outside (If you don't know where this is; now is a great time to find out just in case anything else ever bursts or leaks). Shut off water.
b. Feel piping and try to locate the frozen section of piping. Freezing usually occurs in the fittings (or turns of the pipe) usually not in straight sections of pipe.
c. If piping is in a crawl space, or a basement, consider setting up a space heater to warm the air around the piping.
d. If you found exactly where the freezing occurred (always have a fire extinguisher around just in case), try:
i. Using a hair dryer, and pass over the piping back and forth slowly and patiently.
ii. A heat gun can be used for this. iii. Wrap warm, wet cloth around the pipes. e. When flow resumes, turn off all noise making appliances or items, and look and listen for possible breaks or leaks in the system.
f. Freezing usually occurs in crawl spaces, not underground piping.
3. What to do if pipes burst!
a. This is what a pipe will look like if it's burst, and you'll probably notice the water everywhere, too!
b. Immediately locate shut off valve, and turn it off. Turn off the water heater. If shut off does not work, call local water supplier and have them come out to shut off the water.
c. Make sure to clear a workspace around the pipes for the plumber.
Check out "Morganized" Plumbing here: www.morganizedplumbing.com.