In this video I thaw out a frozen outside tap and also the main incoming water pipe for a domestic property. Remember that copper pipes can split during the freezing process, as the water expands. When the water thaws it can cause a flood, so always be aware of the dangers of freezing copper pipes and take precautions if necessary. A frozen pipe can be thawed out using a hot water bottle, a heat gun, hair dryer or you can even use a blow torch set to low heat, providing your pipes are metal (do not use a blowtorch on plastic pipes).
An outside tap cover is a great idea and can prevent pipes and taps from freezing- https://www.youtube.com/watch?v=-YzY-T3Y_l0