Outdoor pipes will freeze if the temperatures drop below 20 degrees Fahrenheit and stays there for long periods. You can prevent frozen pipes outdoors and there are ways to thaw frozen outdoor pipes correctly so you don't cause the pipes to burst.
How Faucets Freeze
When you leave water sitting in the faucet during the winter, the water will freeze when the temperatures drop below freezing. Not only will the water freeze in the faucet, but it could freeze in the indoor pipe if the freeze is severe enough and the pipe is close to the exterior wall or in a crawl space. Before winter sets in, you need to protect your outdoor faucets so you don't have any chance of freezing.
Turn off the water supply to the outdoor faucet. All pipes leading to a faucet have a shut off valve, which is normally found indoors in a basement or crawl space. Open up the faucet outside so the water drains out of the pipe leading to the faucet and the faucet itself so there will be no water left in the pipe or faucet to freeze. This will prevent the faucet from freezing and bursting.
When you have frozen faucets or pipes leading to the faucet, you risk the chance of having the pipe connected to the faucet or the faucet itself bursting under the pressure of the frozen water. When the faucet or pipe freezes, the ice inside will expand. As the ice expands, it puts pressure on the pipe or faucet, which will burst, shooting water everywhere.
Turn off the water supply leading to the faucet. If you leave the water on while you are thawing out the pipe and faucet, you risk the chance of causing the pipe to burst under pressure. Open the faucet outdoors. Use a hair dryer to unthaw the faucet and pipe leading to the faucet. Do not stand in water when you perform this type of thawing. Start thawing the pipe at the open faucet and work your way back over the pipe until you have no more ice in the pipe.
Do not use any devices that have an open flame to thaw out the faucet and pipe. This includes a charcoal stove, propane heater and a blowtorch. These devices can start a fire and produce carbon monoxide if used to heat the pipe indoors that is attached to the outdoor faucet. When thawing out the pipe, you may find out that the pipe or the faucet is already cracked. If this happens, you will need to replace the pipe and/or faucet.