How to Prevent Frozen Pipes (and What to Do If They Freeze)

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A frozen pipe can turn into a burst pipe in a matter of hours, and a burst pipe can pour hundreds of gallons of water into your home before you notice. The repairs and water damage can easily cost thousands of dollars.

The good news: frozen pipes are one of the most preventable winter disasters. This guide shows you exactly how to protect your pipes, how to tell if one has frozen, how to thaw it safely, and what to do if the worst happens.

Why pipes freeze (and burst)

When water freezes, it expands. In a pipe, that expansion builds up enormous pressure between the ice blockage and the closed faucet. The pipe often bursts not where the ice is, but somewhere along that pressurized section, which is why a burst can happen inside a wall where you can't see it.

Pipes most at risk:

Pipes in unheated areas: crawl spaces, attics, garages, unfinished basements
Pipes along exterior walls, especially under kitchen and bathroom sinks
Outdoor faucets, hose bibs and sprinkler lines
Pipes near drafts: gaps around cables, dryer vents or foundation cracks
Homes in southern states, where pipes are often less protected because hard freezes are rare

At what temperature do pipes freeze?

Water freezes at 32°F, but pipes inside a home are somewhat protected. A widely used rule of thumb: pipes are at serious risk when outdoor temperatures drop to about 20°F or below, especially for several hours or overnight. Pipes in unheated or drafty spots can freeze at higher temperatures, and wind chill against exterior walls makes it worse.

Before winter: 8 ways to prevent frozen pipes

1. Insulate exposed pipes. Foam pipe sleeves are cheap, easy to install and slip right over pipes in basements, crawl spaces, attics and garages. Focus on hot and cold lines.

2. Use heat cable on high-risk pipes. For pipes that freeze every year, a thermostatically controlled heat cable (heat tape) warms the pipe automatically when it gets cold. Choose one that's UL-listed and follow the instructions exactly.

3. Disconnect garden hoses and shut off outdoor faucets. Drain the hoses and store them. If your outdoor faucet has an indoor shut-off valve, close it and open the outside faucet to drain the line. Add an insulated faucet cover.

4. Blow out your sprinkler system. In-ground irrigation lines need to be drained or blown out before the first hard freeze.

5. Seal cold drafts near pipes. Caulk or foam gaps where pipes, cables and vents pass through exterior walls and the foundation. Close crawl-space vents in winter if your home's design allows it.

6. Add insulation to unheated spaces. More insulation in the attic, crawl space and around the rim joist (where the house sits on the foundation) helps keep pipes above freezing.

7. Find your main water shut-off valve now. If a pipe ever bursts, you'll need to shut off the water fast. Find the valve (often where the water line enters the house: basement, crawl space, utility room or near the water heater), make sure it turns, and show everyone in your household.

8. Consider a smart leak/freeze sensor. Small, inexpensive sensors can alert your phone when the temperature drops near a pipe or water is detected. They are very useful for vacation homes or if you travel in winter.

During a cold snap: what to do

When temperatures drop toward the low 20s or below:

✅ Let faucets drip. A slow drip from faucets on exterior walls (both hot and cold) relieves pressure and keeps water moving.
✅ Open cabinet doors under kitchen and bathroom sinks so warm room air reaches the pipes. (Move cleaning products out of reach of kids and pets.)
✅ Keep the thermostat steady: the same temperature day and night, and never below 55°F.
✅ Keep the garage door closed if water lines run through the garage.
✅ Open interior doors so heat can reach all rooms.
✅ If you're traveling, leave the heat at 55°F or higher and ask someone to check the house. For longer trips, consider shutting off the main water and draining the lines.

Signs a pipe is frozen

🚰 You turn on a faucet and get only a trickle or no water at all
❄️ Frost on a visible pipe
🫧 A bulging or cracked pipe
👃 Odd smells from drains (gases can't escape through the blocked line)
💧 Water stains, damp drywall or puddles: signs a pipe may have already burst

How to thaw a frozen pipe safely

If you think a pipe is frozen but not burst:

Open the faucet the pipe supplies (both hot and cold). As the ice melts, flowing water helps melt the rest, and relieves pressure.
Find the frozen section. Start with pipes on exterior walls or in cold areas closest to the faucet with no water.
Apply gentle heat, working from the faucet end back toward the frozen spot:
- A hair dryer on a warm setting
- An electric heating pad wrapped around the pipe
- Towels soaked in hot water, replaced as they cool
- A space heater placed safely nearby (kept away from anything flammable and never left unattended)
Keep heating until full water pressure returns.
Check other faucets: if one pipe froze, others may have too.

🚫 Never use:

A blowtorch, propane torch or any open flame: it can start a fire, damage the pipe or turn trapped water to steam and burst the pipe.
Kerosene or propane heaters indoors.
Electrical devices near standing water.

Call a licensed plumber if:

You can't find or reach the frozen section (it may be inside a wall)
The pipe doesn't thaw
You see any cracks, bulges or leaks

If a pipe bursts: what to do right now

Shut off the main water valve immediately.
Turn off electricity to the affected area if water is near outlets, appliances or the electrical panel, but only if you can do so safely without standing in water.
Open faucets to drain remaining water and relieve pressure.
Call a plumber. Many offer 24/7 emergency service.
Remove standing water and move valuables out of the way. Start drying the area with fans and a dehumidifier. Mold can begin growing within 24 to 48 hours.
Take photos and videos of the damage before cleanup for your insurance claim.
Call your homeowners insurance company.

👉 See what repairs cost: Frozen Pipe Repair Cost

Does homeowners insurance cover frozen pipes?

Many standard homeowners policies cover sudden and accidental water damage from a burst pipe. However, claims can be denied if the insurer decides the damage happened because of neglect, for example, leaving the heat off in an empty house or not maintaining your plumbing. Policies vary, so check yours before winter and keep your heat on.

Frequently asked questions

At what temperature should I drip my faucets? When outdoor temperatures are forecast to drop to around 20°F or below, or higher if your pipes are in unheated or drafty areas.

Will pipes freeze at 32°F? Pipes inside a heated home usually won't freeze at 32°F. Pipes in unheated spaces, outdoor faucets and pipes along exterior walls can freeze at or slightly below freezing, especially overnight or in wind.

How long does it take for pipes to freeze? Exposed pipes in very cold conditions can freeze in a matter of hours, sometimes as few as 6 to 8 hours in extreme cold. That's why overnight cold snaps are especially dangerous.

Can frozen pipes thaw on their own? They can as temperatures rise, but waiting is risky: the pipe may already be damaged, and you won't see a leak until it thaws. Thaw it carefully and check for damage.

Should I turn off my water when I go on vacation in winter? For long trips, yes. Shut off the main valve and open faucets to drain the lines, while keeping the heat at 55°F or higher.

The bottom line

Preventing frozen pipes costs very little: insulate exposed pipes, shut off outdoor faucets, seal drafts, keep your heat at 55°F or higher, and let faucets drip during cold snaps. Know where your main shut-off valve is, and if a pipe does freeze, thaw it gently. Never with an open flame.

Getting your whole home ready? Use our Complete Winterize Your Home Checklist.