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Knowing how to prevent frozen pipes is one of the cheapest ways to avoid one of the most expensive winter repairs a homeowner can face. When water freezes inside a pipe, it expands, builds pressure, and can split copper or plastic lines wide open. The pipe usually doesn’t leak until it thaws, which means the damage often shows up as water pouring through a ceiling or flooding a basement.
This guide covers why pipes freeze and burst, which pipes in your house are most at risk, the 9 steps that keep pipes from freezing, the simple routine I follow every time the temperature drops to 32°F, how to protect your pipes when you’re away, and exactly what to do if a pipe freezes or bursts anyway.
Understanding how to prevent frozen pipes is essential for every homeowner during winter. By following simple steps, you can effectively protect your plumbing.
WHAT’S IN THIS GUIDE
Why Pipes Freeze and Burst
Water expands as it freezes, and that expansion puts tremendous pressure on whatever is holding it, whether that’s a copper line or a plastic one. Source: American Red Cross — Preventing and Thawing Frozen Pipes
Here’s the part most people don’t realize: a pipe usually doesn’t split right where the ice forms. Once an ice blockage builds up, it traps the water between the ice and the closed faucet at the end of the line. As more ice forms, the pressure in that trapped section climbs until the weakest spot gives way. That’s why a pipe can burst several feet away from the coldest spot, and it’s also why keeping water moving through the line is one of the most effective ways to keep pipes from freezing.
Which Pipes Are Most at Risk
Not every pipe in your house is in danger. The ones that freeze first are the ones exposed to cold air with little or no heat around them:
- Outdoor hose bibs, swimming pool supply lines, and sprinkler lines
- Pipes in unheated spaces like basements, crawl spaces, attics, and garages
- Pipes inside kitchen and bathroom cabinets, especially on exterior walls
- Any pipe that runs along an exterior wall with little or no insulation
There are several methods on how to prevent frozen pipes that are easy to implement.
If you have a sink on an outside wall, that’s usually the first place to watch. The cabinet doors trap the pipes in a small, cold pocket of air with almost no heat from the rest of the room reaching them. Source: American Red Cross — Preventing and Thawing Frozen Pipes
My 32-Degree Routine
I’ve lived through plenty of Indiana winters in Greenwood, and I’ve never had a pipe freeze. I credit that to a simple routine I follow every time the forecast hits 32°F or lower overnight.
First, I leave one faucet running with a very light, steady stream. Not a slow drip, but a thin stream about the width of a pencil lead. A drip lets the water sit still between drops, while a steady stream keeps water moving through the line the whole night. Second, I open every cabinet door under every sink in the house so warm room air can reach the pipes inside.
That’s my whole approach to how to keep pipes from freezing. It takes less than a minute, it costs pennies in water, and it covers the two weak spots most houses have: still water in the lines and cold air trapped around the pipes. Most experts put the real danger zone lower, around 20°F, but starting at 32°F gives you a safety margin on the nights the forecast turns out colder than expected.
How to Prevent Frozen Pipes in 9 Steps
Steps 1 through 5 are one-time fall prep. Steps 6 through 9 are what you do when a hard freeze is on the way.
Step 1: Disconnect hoses and shut off outdoor faucets
Disconnect and drain every garden hose before the first hard freeze. A hose left connected traps water in the faucet, and that trapped water can freeze and split the pipe inside the wall, even on a frost-free faucet. If your outdoor faucet has a shutoff valve inside the house, close it and open the outdoor faucet to drain the line. An insulated outdoor faucet cover adds an extra layer of protection, especially on older standard faucets. If your outdoor faucet is already leaking or cracked, our guide on how to replace a hose bib walks through upgrading to a frost-free model, and if you have an irrigation system, see how to winterize your sprinkler system.
Step 2: Insulate exposed pipes
In this section, we will explore how to prevent frozen pipes specifically related to outdoor gardening and plumbing systems.
Wrap any pipe in an unheated basement, crawl space, attic, or garage with foam pipe insulation. It slides over the pipe, seals with a built-in adhesive strip, and cuts easily with scissors. Measure the pipe’s outside diameter first, since a sleeve that’s too loose won’t hold heat. Insulation doesn’t add heat; it slows down heat loss, which buys your pipes time on a cold night.
Step 3: Seal drafts near pipes
Cold air leaking in around a pipe can freeze it even when the rest of the room is warm. Check where pipes pass through exterior walls, the rim joist in your basement, and around dryer vents and cable lines. Fill gaps with expanding foam or caulk. Our guide on how to seal windows and doors for winter covers the rest of the drafts worth fixing while you’re at it.
Step 4: Add heat cable to problem pipes
If you have a pipe that has frozen before or one you can’t keep warm any other way, like a line in a crawl space or an unheated garage, install pipe heat cable. A thermostat-controlled cable turns on automatically when the temperature drops near freezing. Choose a UL-listed product, follow the manufacturer’s directions exactly, and never wrap a cable over itself unless the instructions say it’s allowed.
Step 5: Keep the garage door closed
If any water lines run through your garage, keep the big door closed as much as possible in winter. A garage can drop to near outdoor temperatures within a few hours with the door open.
Step 6: Open the cabinet doors under your sinks
On nights at or below freezing, open the cabinet doors under your kitchen and bathroom sinks so warm air from the room can circulate around the pipes. This is one half of my 32-degree routine and the easiest step on the list. Move cleaning products up and out of reach if you have kids or pets. Source: Iowa State University Extension — Preventing and Thawing Frozen Pipes
Step 7: Let one faucet run at a thin stream
Running water through a pipe, even at a trickle, helps prevent it from freezing. Pick the faucet served by the most exposed pipes, usually a sink on an outside wall, and open the cold side to a thin, steady stream. I use a stream rather than drips, because a steady stream never lets water sit still in the line. It also relieves pressure if an ice blockage does start to form. Source: American Red Cross — Preventing and Thawing Frozen Pipes
Step 8: Keep your thermostat steady day and night
Lowering the heat at night saves a little on your bill, but during a deep cold snap it can let the spaces behind walls and inside cabinets cool down enough to freeze. Keep the thermostat at the same temperature day and night until the cold passes. If you’re struggling to keep the house warm, a clogged furnace filter could be the reason. See our guide on how to choose a furnace filter. Source: Iowa State University Extension — Preventing and Thawing Frozen Pipes
It’s crucial to maintain awareness of how to prevent frozen pipes by regularly inspecting plumbing during the colder months.
Step 9: Know where your main water shutoff is
Find your main shutoff valve now, before you need it. It’s usually where the water line enters the house, in the basement, crawl space, or utility room, or near the water heater. Make sure it turns, and show everyone in the house where it is. If a pipe bursts, every minute the water stays on adds to the damage.
How to Protect Your Pipes When You’re Away
If you’re leaving for a few days or more during cold weather, leave the heat on and set it no lower than 55°F. Don’t turn the heat off to save money. Source: American Red Cross — Preventing and Thawing Frozen Pipes
For those who travel often, learning how to prevent frozen pipes while away from home is vital to avoid costly repairs.
For longer trips, shut off the main water supply and open the faucets to drain the lines, so there’s no standing water left to freeze. Ask a neighbor or friend to check the house if a deep cold snap hits while you’re gone. A smart water leak and freeze sensor placed near your most exposed pipes will send an alert to your phone if the temperature drops too low or water starts leaking, so you can act before a small problem turns into a flooded basement.
How to Tell If a Pipe Is Frozen
Watch for these signs on a cold morning:
- You turn on a faucet and only a trickle comes out, or nothing at all
- Frost is visible on an exposed pipe
- A pipe looks bulged or has a small crack
- You smell something odd from a drain, which can mean a frozen line is blocking it
- You hear banging, gurgling, or whistling in the pipes
If only one faucet is affected, the frozen section is somewhere along the line feeding that fixture. Check other faucets too, since if one pipe froze, others may have as well. Source: Iowa State University Extension — Preventing and Thawing Frozen Pipes
How to Thaw a Frozen Pipe Safely
If you think a pipe is frozen, act quickly, but go slowly with the heat. Thawing a pipe too fast can damage soldered joints, which are the weakest points in the line. Source: University of Missouri Extension — Precautions to Avoid Frozen Pipes
Step 1: Open the faucet
Open the faucet on the frozen line first. As the ice melts, water will start to flow, and the moving water helps melt the rest of the blockage. An open faucet also gives the pressure somewhere to go.
Step 2: Apply gentle heat, starting near the faucet
Start warming the pipe at the faucet end and work back toward the frozen section. Use a hair dryer, an electric heating pad wrapped around the pipe, a space heater with automatic tip-over shutoff kept a safe distance from anything flammable, or towels soaked in hot water. Keep applying heat until full water pressure returns. Source: Iowa State University Extension — Preventing and Thawing Frozen Pipes
Never use an open flame
Never use a blowtorch, propane heater, kerosene heater, charcoal stove, or any open flame to thaw a pipe. Beyond the fire risk, a torch can heat a pipe so fast that the water inside turns to steam and the pipe bursts. Don’t use boiling water either. Be especially careful with plastic pipe, which melts at a much lower temperature than copper. Source: Utah State University Extension — Advice to Prevent Frozen Pipes
Call a licensed plumber if you can’t find the frozen section, can’t reach it, or can’t get it to thaw.
What to Do If a Pipe Bursts
If a pipe bursts, move fast:
- Shut off the main water supply immediately
- If water is near outlets, cords, or your electrical panel, shut off power to that area at the breaker, and stay out of standing water if you can’t do it safely
- Open faucets to drain the remaining water out of the system
- Call a licensed plumber to repair the pipe
- Take photos and video of the damage before you clean up, for your insurance claim
- Start drying everything out right away with fans and a dehumidifier
Speed matters with the cleanup. Mold can start growing within 24 to 48 hours on wet drywall, carpet, and wood. Our guides on how to check your home for water damage and mold in your house walk through what to look for after the water’s gone.
Frequently Asked Questions About Frozen Pipes
At what temperature do pipes freeze?
Water freezes at 32°F, but pipes inside your house usually don’t freeze the moment it hits 32°F outside. The risk climbs when outdoor temperatures drop into the low 20s or below for several hours, especially for pipes in unheated spaces or along exterior walls. I start my routine at 32°F to leave a safety margin.
Should I drip hot or cold water to keep pipes from freezing?
Cold. Run the cold water side of the faucet served by your most exposed pipes. There’s no need to run hot water and pay to heat it. If you have a single-handle faucet, set it all the way to cold.
Does leaving a faucet dripping really prevent frozen pipes?
Yes. Moving water is much harder to freeze than still water, and an open faucet relieves the pressure that builds up behind an ice blockage, which is what actually bursts the pipe. I use a thin, steady stream instead of a drip so the water never sits still in the line.
Can pipes freeze in one night?
Yes. A pipe in an unheated crawl space, garage, or exterior wall can freeze in a single night when temperatures drop well below freezing, especially with wind. That’s why it’s worth opening cabinet doors and running a faucet any night the forecast hits 32°F or below.
Should I open cabinet doors at night in winter?
Yes, on any night at or below freezing. Opening the cabinet doors under your sinks lets warm room air reach pipes that are otherwise trapped in a cold, closed space. It’s free and takes a few seconds.
Does homeowners insurance cover frozen pipes?
Many policies cover sudden water damage from a burst pipe, but coverage can be denied if the home was left unheated or the damage was caused by a lack of maintenance. Every policy is different, so check yours or call your agent before winter.