A hard freeze isn't evenly distributed inside a house. Pipes running through heated living space are generally fine no matter what the thermometer says outside. The ones that freeze are the ones in unheated or barely heated places: an attached garage, a crawl space with open vents, an unfinished attic, a rim joist, and any line running through an exterior wall where insulation is thin or missing behind it. Wind makes it worse, because air moving through a vent or a gap carries heat away far faster than still cold air does.
Hose bibs sit in the worst position of all, since half the assembly is literally outdoors and the rest of it passes through the coldest part of the wall. That is why the first hard freeze of the season claims so many of them. Once you know which lines in your house are exposed, the whole problem narrows down considerably. You aren't protecting all the plumbing in the building. You are protecting a short list of specific spots, and that list doesn't change much from one winter to the next.
Disconnect every garden hose in the fall and drain it. A hose left attached traps water in the bib and stops it from draining back out, which is enough to freeze and split the assembly even on a bib that was designed to resist exactly that. It is the single most preventable winter plumbing failure there is. This one step heads off a large share of the calls that come in every year after the first cold night, and it takes about as long as walking the perimeter of the house.
While you are out there, look for the rest of it. If there is a separate interior shut-off for the outdoor line, close it and open the bib outside so any remaining water drains out. Check the crawl space hatch and any vents, and look at whether exposed pipe in the garage or rim joist has insulation on it. Pipe insulation is cheap and it slows heat loss, though it is worth knowing that insulation only delays freezing on a pipe with no heat source. It doesn't add warmth.
When the forecast turns genuinely cold, keep the house heated steadily rather than setting the thermostat back overnight to save a little. Open the cabinet doors under sinks that sit against exterior walls so room air can reach the supply lines behind them. Keep the garage door closed, especially if there is plumbing in that wall or ceiling. If a room is closed off and unheated, opening the door to it is the simplest way to feed it a little warmth from the rest of the house.
Letting a faucet run a small steady trickle at the most exposed fixture also helps, for two reasons: moving water is slower to freeze, and an open faucet gives pressure somewhere to go if ice does form in the line. It is a cold-snap measure, not a whole-winter habit. Run it at the fixture farthest along the most exposed run, and turn it off once temperatures come back up, since there is no reason to send water down the drain the rest of the season.
The usual sign is one fixture with no water, or barely any, while the rest of the house runs normally. That tells you roughly where to look, since the frozen section sits somewhere along the run feeding that fixture, and it is almost always in one of the cold spots you already know about. Open the affected faucet before you do anything else, so melting ice has somewhere to release pressure as it goes rather than building it up behind the plug.
Warm the area gently with a hair dryer, a heat lamp, or a space heater kept a safe distance from anything combustible. Work from the fixture end back toward the frozen section rather than the other way around. Never use an open flame on a pipe, in a crawl space, or anywhere near framing and insulation. If a section won't thaw, or you can't reach it, that is a call for a plumber, and it is worth knowing where the main shut-off is before the thaw arrives.
Ice expanding inside a pipe does the damage, but the pipe rarely announces it while it is still frozen. The split stays plugged with ice and nothing leaks. Then the line thaws, water starts moving again, and it comes out of the crack under full pressure, often in a wall or crawl space where nobody is watching. This is why a frozen pipe isn't really over when the water comes back on. It is over when the run has thawed completely and stayed dry.
So be present for the thaw. Have the main shut-off located and be ready to use it, watch the ceilings and walls near the exposed run for a few hours, and check the crawl space or basement afterward rather than assuming. If water does escape into the structure, understand that the plumbing repair and drying out the building are two different jobs. Get the pipe fixed first, then deal with what got wet, and don't let the second part wait.
No, just during a hard freeze. Moving water is slower to freeze, and an open tap gives pressure somewhere to go if ice does start forming, so a thin steady stream at the far end of an exposed run is worth it while temperatures are extreme. Once they climb back up, shut it off. Running water through a mild week accomplishes nothing at all.
It isn't the ice pushing outward on the pipe wall that usually does it. As an ice plug grows, it traps water between itself and a closed faucet, and pressure builds in that trapped section until the pipe gives way, often at a point away from the ice itself. That is exactly why opening the faucet on a frozen line matters.
Exposed pipe in a vented crawl space is one of the most common freeze locations there is, and moving air through those vents makes it worse. Many homeowners cover the vents through the coldest stretch and open them again in spring. Insulating the pipes themselves helps too. If any combustion appliance lives down there, don't seal the space up without asking a professional first.
Learn where the main shut-off and fixture stops hide in a Utah home, and how to test them before a leak. Plumbing 801 on the Wasatch Front, 801-644-9000.
Read the guide →Scale in the water heater, stiff valves, and weak-feeling fixtures are hard water at work. Plumbing 801 covers Salt Lake to Weber County. Call 801-644-9000.
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