Frost-free faucets are common on many houses and buildings and are designed to help minimize the number of frozen pipes in winter of exterior faucets. Frost-free faucets are designed with the shutoff valve inside the building, allowing the warmth from inside to keep the water from freezing and any excess water is drained and does not pose a problem. Problems happen when these faucets are installed improperly. As shown below the frost-free faucet should be installed at a downward angle to allow excess water to drain. When water is trapped from being angled in reverse it allows the faucet to freeze and then crack.
Also if a hose is left on in the winter it can also create a similar effect and not allow water to drain properly and freeze.
See how a standard frost-proof faucet works here.
When some portion of this system fails due to either defect, improper use, or installation it is usually hard to detect. When the water is left in the portion of the faucet that should drain and it freezes it will usually cause a crack or break in the pipe, but it is not noticed at the time that there is a problem because the water is shut off. But when warmer weather comes and the faucet is turned back on for gardening or sprinklers the water can travel through this crack. But then the valve is shut off and the individual goes back inside to attend other business and they notice water everywhere. They have a hard time detecting where the leak came from because the water is shut off outside and the leak is in the wall. The faucet will only leak when the water valve is turned on and allows water to pass where the crack is and when the valve is outside and the crack inside it is common that the leak will go unnoticed until it is too late.
To prevent this, make sure your frost-free faucet is installed at a downward angle and hoses are not left on in cold weather. But if something like this does happen give us a call and we can clean up the mess for you as noted on our water damage page.
Hope everyone has a safe and Merry Christmas and a Happy New Year!