Thrawing out frozen pipes should be done safely so follow this step by step guide on what to do when you run into the problem of having your water or drain pipes freeze. As long as you’re home (and not off vacationing somewhere warm) you can usually fix the problem yourself. Here are some tips on how to thaw your frozen pipes.
Check to make sure the frozen pipe hasn't cracked. When water freezes into ice it expands, so if the water in the pipe is frozen solid it may have expanded enough to actually crack the pipe (in which case you'll need to repair the pipe). However, in many cases a water pipe isn't cracked; it's just blocked
Once you've determined the pipe hasn't split, turn off the water leading to the pipe. In older homes this likely means you'll need to shut off the main water supply coming into your home, while in newer homes intermediate water shut off valves may have been installed, allowing you to isolate the frozen pipe.
Open all of the faucets connected to the frozen pipe to get rid of the cold water in the pipe, minimize pressure and allow the ice/water to flow out of the pipe once it's thawed.
Thaw your pipe by using one of the following methods (depending on what you have available and how easy or difficult it is to get to the pipe).
Wrap the pipe with bath towels or cloths and pour hot water (from the kettle) over the towels. This will apply warmth to a section of the pipe and thaw the ice.
Use a handheld hair dryer to blow warm air onto the frozen section. Prop a small space heater close to the frozen pipe and leave it for an hour
Wrap the frozen pipe with electric pipe heating tape (available at home stores). Run a propane plumbing torch or blowtorch along the frozen pipe.
How to Thaw Frozen Drain Pipes - All the above methods for thawing a frozen water pipe will work for thawing a frozen drainpipe, except for the torches-you don't want to use a torch on a PVC or ABS plastic pipe. Plus, here's a couple of other ways you could thaw a frozen drainpipe.
Pour hot/boiling water down the drain and let it melt the ice.
Snake a piece of rubber tubing down the drain until it hits the ice. Attach the end of the tube that's in your hand to the spout of a boiling kettle of water. The steam from the kettle will travel down the pipe and melt the blockage.