Most homeowners who live in cold climates know it's important to 'winterize' the outside faucets to prevent them from freezing, which can destroy the faucet or lead to a burst pipe. The problem is that many people don't quite get it right - winterizing the outside faucets in the fall seems like a simple thing to do, and it seems like it should be straightforward and easy, but there are a few tricks you need to know to make sure all the water is out.
Garden hoses - First and foremost, disconnect your garden hose from the outside faucet. If you leave your garden hose attached to the faucet, you're asking for trouble.
Frost-free sillcocks with an integral vacuum breaker If you have a properly installed frost-free sillcock with an integral vacuum breaker, you shouldn't have anything to worry about. You should be able to leave the water on to these faucets all year 'round without them freezing. A properly installed frost-free sillcock will have a slight downward pitch, so that when the water is turned off, the water will all drain out of the stem.
When frost-free sillcocks aren't installed with this downward pitch, water will sit inside the stem of the sillcock even when it's turned off. The pitch is a little dramatic in the photo below, but you get the point.
If this water freezes, it can burst the stem of the sillcock. Most homeowners don't know this has happened until the first time they use their faucet in the spring. Once they turn their faucet on, water starts shooting out of the burst stem inside the house, making a big mess while nobody is inside the house to see it. This recently happened to Connecticut home inspector James Quarello while he was inspecting a home. Better him than me, I say.
The fix for an improperly installed frost-free sillcock is to have it re-installed with a slight downward pitch.
Winterizing standard sillcocks With a standard sillcock, the water needs to be turned off and drained out to prevent freeze damage. To do this, you'll need to first turn off the water supply to the faucet from inside the house. Exterior faucets should have a separate shutoff valve inside the house, but not all of them do. On older homes, these valves are typically located at the ceiling somewhere close to the outside faucet. On newer homes, the valves are typically located right next to the main water valve, and they're also usually labeled.
Once the water is turned off inside the house, the outside faucet needs to be opened up. Next, the bleeder cap inside the house needs to be unscrewed - this will allow water to drain out of the pipes. Depending on how the pipe is pitched, the water may drain through the bleeder cap or through the outside faucet. Keep a small bucket handy when you do this, just in case a lot of water needs to drain out of the bleeder. After the water drains out, you can screw the bleeder cap back on and turn off the outside faucet.
Sometimes, two wrongs really do make a right Some older houses in Minneapolis and Saint Paul don't have a shutoff valve for the outside faucet, and the faucets never get winterized... yet they never have a problem with freezing. How can this be?
Here's a hint:
On older houses with no insulation at the rim space, there can be so much heat loss occurring here that the outside faucets never get cold enough to freeze. I call this "two wrongs making a right." It's certainly not a reliable method of preventing freeze damage, but it does seem to work.
Vacuum breakers complicate things The problem with external vacuum breakers (aka backflow preventers) is that they don't allow all of the water to drain out. After the water is turned off and appears to have drained out, the rubber seal in the vacuum breaker will still trap enough water to destroy the vacuum breaker, which will cause water to spray out all over the place when the faucet is used again in the spring.
There are two possible solutions: remove the vacuum breaker in the fall, or drain the water out of the vacuum breaker. If the vacuum breaker will just unscrew from the sillcock, go ahead and take it off in the fall. The problem with this is that vacuum breakers are often designed to be permanently installed. They have a little set-screw on the side that gets tightened down until it breaks off, making it so the vacuum breaker can't be removed. If your vacuum breaker leaks every time you turn on your faucet and you need to replace it, there is still a way to remove it without destroying your faucet - I made a video showing how to do it.
If the vacuum breaker can't be removed or you don't want to hassle with removing it, no problem; there is still a way to drain the rest of the water out. If you look up inside the vacuum breaker, you'll notice that there is a small white plastic post. Just push this post to the side, and the rest of the water will drain out. The video below shows how this works.
If the vacuum breaker doesn't have that white post, it may have a plastic ring that will allow it to drain.
Reuben Saltzman, Structure Tech Home Inspections