Knowing how to keep pipes from freezing is a home preparedness skill that protects your walls, floors and savings from one of the costliest kinds of damage winter brings. A crack an eighth of an inch wide can release about 250 gallons of water a day. That water soaks insulation, drywall and subfloor, often before anyone sees a drop. The work to prevent it is cheap and mostly fits into one afternoon, and it protects you and your family every cold night after that.
Maybe you own an older house with a crawl space. Maybe you rent an apartment where the kitchen sink sits on an outside wall. Either way, the best time to act is fall, before the first hard freeze. The second best time is the day a cold snap shows up in the forecast. If the cold is already here, the same steps still work, and you simply do them faster.
Start by finding your main water shutoff valve today and tying a bright tag to it. When you know where it is and that it turns, you can stop a burst in under a minute.
Why Pipes Freeze and Which Ones Go First
Knowing which pipes freeze first lets you spend your time and money on the few runs that matter. You get a short list of weak spots in your own home. Every step that follows, from foam sleeves to thawing, builds on that list.
The Temperatures That Matter
Water freezes at 32 degrees F. The pipes inside your home usually stay safe because warm room air surrounds them. Trouble starts when the outside temperature drops to about 20 degrees F, especially for several hours or overnight. Wind makes it worse because it pulls heat out of walls and crawl spaces faster. A pipe in a cold pocket can freeze even while the thermostat in the hall reads 68.
The Pipes Most at Risk
- Exterior walls. Pipes inside an outside wall sit inches from the weather, with only siding and some insulation for protection.
- Crawl spaces and basements. An unheated crawl space drifts toward the outside temperature, and supply lines often run right along its floor joists.
- Attics. Plumbing for an upstairs bath sometimes crosses the attic, a space built to stay cold in winter.
- Garages. An attached garage often holds the water heater, a laundry line or the pipe that feeds an outdoor tap.
- Sinks on outside walls. Kitchen and bathroom sinks against an outside wall have pipes shut inside a cabinet, away from room heat.
- Mobile homes. Supply lines run under the floor behind thin skirting, so a mobile home needs the most protection of any housing type.
- Outdoor taps and lines. Hose bibs, sprinkler lines and pool lines are fully exposed to the cold.
Walk your home with this list and a flashlight. If you live in an apartment, check the sinks and any closet that backs onto an outside wall. If you own a house, add the crawl space and the spot where the water line enters the foundation.
Pressure: Why a Frozen Pipe Bursts
Most people picture ice swelling and splitting the pipe right where it freezes. That is partly true, since water expands about 9 percent as it turns to ice. The real damage usually happens somewhere else, though. An ice plug traps water between itself and a closed tap. As more ice forms, it pushes on that trapped water. Pressure climbs until the pipe gives way at its weakest point. That is why a burst often shows up a few feet from the ice. It is also why a dripping tap helps, because it gives that pressure somewhere to go. The next job is keeping the ice from forming at all.
How to Keep Pipes from Freezing Before the Cold Arrives
A few hours of fall prep keeps most pipes flowing through the whole season. You get a home that rides out an ordinary cold snap with no extra effort. You also get a head start on the outage plan further down the page.
The Fall Checklist
- Foam pipe sleeves. Slide foam sleeves over exposed pipes in the crawl space, basement, garage and under sinks. Measure the pipe first, usually 1/2 or 3/4 inch, and tape the seams so cold air stays out.
- Heat tape or heat cable. Wrap the pipes that still worry you, such as a crawl space line or the supply under a mobile home, with heat cable rated for water pipes. Install it exactly to the maker's instructions, plug it into a grounded outlet and test it each fall.
- Hoses and outdoor taps. Disconnect garden hoses, drain them and store them. A connected hose holds water against the tap, and that water can freeze back into the wall. Close the indoor valve that feeds each outdoor tap if your home has one, open the outside tap to drain it, then cover it with an insulated faucet cover.
- Drafts where pipes enter. Seal gaps around pipes where they pass through walls and floors with caulk or expanding foam. A gap the size of a pencil can freeze a pipe that is otherwise well wrapped.
- Crawl space vents. Close foundation vents for winter with vent covers or foam board cut to fit. Reopen them in spring so the crawl space can dry out.
- Main water shutoff. Find the main valve, usually where the line enters the house, near the water heater or in a box at the curb. Turn it off and back on once so you know it moves, then tag it.
If the main valve will not budge, have a plumber free or replace it now. A stuck valve found in fall is a small bill. A stuck valve found during a burst means water keeps running while you wait for help.
If You Rent
Renters can do most of this work, and much of it costs under twenty dollars. Foam sleeves, a faucet cover and open cabinet doors need no one's permission. Ask your landlord where the main shutoff is and whether you can reach it. In many apartments it sits in a utility closet or a shared basement. Write the answer on an index card and keep it in a kitchen drawer. Report cold drafts or bare pipes in writing before winter, since protecting the building's plumbing is usually the owner's job. A rental also has an advantage. Shared walls with heated units keep many interior pipes warmer than they would be in a detached house.
If You Live in a Mobile Home
A mobile home has the most exposed plumbing, and it is also the easiest to reach. Check the skirting for gaps and patch them so wind stays out from under the floor. Make sure the heat tape on the main supply line works before the first freeze. Because the pipes sit just under the floor, you can inspect the whole system in one short crawl. With the weak spots wrapped and sealed, the next job is keeping water moving when the furnace or the power quits.
Keeping Pipes Flowing Without Heat or Power
A home can lose heat for hours or days during a winter storm, and the pipes can still come through if water keeps moving and warm air keeps reaching them. You get steps that buy time in an outage, plus a fallback for when the house must sit cold too long. Thawing and burst repair come after that.
Drip, Open and Hold Steady
- Let taps drip. Open faucets on outside walls to a thin, steady drip from both hot and cold lines. Moving water is slow to freeze, and an open tap releases pressure if ice forms anyway. On a single-handle faucet, set the handle to the middle so both lines run.
- Open cabinet doors. Open the doors under sinks so room heat reaches the pipes. Move cleaners up to a high shelf first if you have small children or pets.
- Hold the thermostat steady. Keep the same setting day and night during a cold snap. A lower overnight setting lets the walls cool at the coldest hour. If you travel, leave the heat at 55 degrees F or higher.
How to Keep Pipes from Freezing Without Heat
If the furnace fails but the power stays on, an electric space heater can protect the coldest room. Choose one with a tip-over shutoff, plug it straight into a wall outlet and keep it three feet from anything that burns. Aim it toward an open sink cabinet or a cold wall, then check on it often. Keep interior doors open to rooms with plumbing so warm air can reach them. Keep the garage door closed if the garage holds pipes or the water heater. Call for furnace repair right away, since these steps buy hours rather than weeks.
How to Keep Pipes from Freezing Without Power
In a power outage, the furnace, the space heater and the heat tape all stop at once. Dripping taps and open cabinets become your main tools, so start them as soon as the lights go out. Use only heat sources built and vented for indoor use, such as a fireplace or an installed wood stove. Keep grills, camp stoves and outdoor heaters outside, every time. They make carbon monoxide, a gas you cannot see or smell, and it can kill a sleeping family. Run a generator at least 20 feet from doors and windows, and keep a battery-powered carbon monoxide alarm on every sleeping floor. Learning how to heat your home without power safely protects both your family and your plumbing.
If you are on a private well, the pump stops when the power does, so a drip will not flow. Open a tap or two anyway to relieve pressure in the lines. For a short outage of a day or so, these steps usually carry the pipes through. Preppers in cold country often keep a few days of stored water and food on hand for exactly this stretch, because a drained system means no running water until heat returns.
Draining the System When You Must Leave
If the house will go unheated for several days, such as a one week outage in hard cold, drain the plumbing. Shut off the main valve first. Turn the water heater off, setting a gas unit to off or pilot and switching off the breaker for an electric unit. Open every tap, hot and cold, starting on the top floor and finishing at the lowest tap in the house. Flush each toilet and hold the handle down until the tank empties, then sponge out what remains.
Next, drain the water heater. Let the water cool for a few hours if you can, since it starts out hot enough to scald. Attach a garden hose to the drain valve near the bottom of the tank, run it to a floor drain or outdoors and open the valve. Open a hot tap upstairs so air can enter and the tank drains faster. Pour a cup of nontoxic plumbing antifreeze into each toilet bowl and sink trap, and leave the taps open.
When you return, close the taps and the drain valve, then turn on the main. Refill the water heater completely before you restore its power. An electric heater switched on while empty can burn out its elements in minutes.
Thawing a Frozen Pipe and Stopping a Burst
Quick, careful action turns a frozen pipe back into a working one before it splits. If a pipe has already burst, it holds the damage to one room. You get the signs to watch for, a safe way to thaw and an ordered plan for the first hour after a burst.
Signs a Pipe Is Frozen
Turn on a tap. If only a trickle comes out, or nothing at all, while other taps run normally, the line to that tap is likely frozen. Look for frost on an exposed pipe or a slight bulge in it. A toilet that will not refill points to a frozen supply line. If no tap in the house works, the freeze is probably near the spot where the main line enters.
Thaw From the Tap End
Open the affected tap first so melting water has a way out. Apply heat at the tap end and work back toward the frozen section. Use a hair dryer, an electric heating pad, or towels soaked in hot water and wrapped around the pipe. An electric space heater aimed at a cabinet or a cold wall also works. Keep all heat electric or water-based. A torch or other open flame can set fire to the framing inside a wall, and it can heat trapped water fast enough to split the pipe. Keep warming until full pressure returns.
Once the water flows, watch the pipe closely for drips. A pipe that froze may have cracked, and the leak only appears after it thaws. Keep that tap dripping for the rest of the cold snap. If you cannot find or reach the frozen section, raise the thermostat, open nearby cabinets and call a plumber.
The First Hour After a Burst
Shut the main water valve first. Water stops flowing the moment you close it, so every second counts. Turn off the water heater next so it does not run on an empty or draining tank. If water is near outlets or appliances, switch off that circuit at the panel only if you can stand somewhere dry. Otherwise, call your electric utility.
Open the lowest taps in the house to drain what is left in the lines. Move rugs, electronics, papers and photos out of the wet area. Photograph and film the burst pipe and every wet surface before you clean up, because your insurer will want the record. Then mop, run fans and call a plumber and your insurance company. Mold can start growing within 24 to 48 hours, so drying the room quickly protects the walls and the air your family breathes.
Three Steps to Take This Week
- Find, test and tag your main water shutoff.
- Wrap every exposed pipe on your weak-spot list and cover your outdoor taps.
- Decide which taps you will drip and which room you will heat if the power fails.
Frozen pipes are one part of a full winter plan. Learning how to prepare for a winter storm covers power, food, water and travel alongside the plumbing.
