My family learned the hard way about frozen pipes. Long ago, as new homeowners, we left our garden hose connected to the spigot all winter. The first nice day in April I decided to wash the car.
I turned the spigot knob and heard the rush of running water, but nothing came out the hose. Hmmmm. Soon my wife yelled from inside, "There's water gushing out of the wall!"
With the hose attached, water had been trapped inside the spigot and pipe all winter. When a cold snap came, the water expanded and split the pipe about 18 inches inside from the outdoor wall. Because the spigot remained unused, we had no way of knowing there was trouble until I turned it on, sending water coursing through the pipe.
I cut out a large section of wallboard just to access and replace the pipe. Then I had to replace, tape, mud, sand, and paint the wallboard. What a hassle.
Read PEMCO's tip sheet, "Five easy last-minute tips to prevent cold-weather woes