What Temperature Causes Pipes to Freeze and Break?
Last updated October 26, 2026
The short answer
The Freezing Threshold
Water freezes at 32 degrees Fahrenheit, but your pipes do not usually freeze the moment the air hits that mark. The water inside needs to lose enough heat to drop to 32 degrees, which takes time. In most homes, the risk becomes serious when the outdoor temperature stays below about 20 degrees for several hours.
The exact freezing point also depends on where the pipe runs. Exposed pipes in unheated crawl spaces, garages, or exterior walls freeze faster than pipes tucked inside warm cabinets. A pipe with a slow drip or some insulation can resist freezing at slightly lower temperatures. If the air around the pipe stays below 32 degrees long enough, ice will form.
Why Pipes Break
Ice takes up more space than liquid water. When water freezes inside a pipe, it expands, and that expansion pushes against the pipe walls. A metal or plastic pipe can stretch a little, but eventually the pressure becomes too much. The pipe can crack or split at its weakest point.
The break often happens after the ice thaws, not while it is still frozen. As the ice melts, the water flows out through the crack. That is why you might not see a leak until the weather warms up. The pressure from the expanding ice also explains why a small crack can turn into a major leak once the water is flowing again.
- Keep garage doors closed if water lines run through the garage.
- Open cabinet doors under sinks to let warm air reach the pipes.
- Let a faucet drip slowly during extreme cold to keep water moving.
- Wrap exposed pipes with foam insulation or heat tape.
- Know where your main water shutoff valve is located.
What You Can Do Before a Freeze
Prevention is easier than cleanup. Insulate pipes in unheated areas, seal gaps that let cold air in, and keep a slow drip on faucets when temperatures plunge. If you leave home for several days in winter, set the thermostat no lower than 55 degrees Fahrenheit. That keeps the indoor temperature above freezing throughout the house.
If you live in Arlington, write down where your shutoff valve is and how to turn it off. That simple step saves time if a pipe does break. Also consider draining outdoor hoses and shutting off outdoor spigots before the first hard freeze. Taking these steps now reduces the chance of a burst pipe later.
What to Do If a Pipe Bursts
If you notice a leak, shut off the main water valve right away. Then open the faucets to drain the remaining water and relieve pressure. Turn off the electricity to any appliances that might be near the water. Move valuables and furniture away from the wet area if you can do so safely.
Once the water is off, call the pros. A burst pipe can dump a lot of water quickly, soaking walls, floors, and personal belongings. The longer the water sits, the more damage it does. Local water damage pros have the tools to dry out the space and check for hidden moisture.
- Shut off the main water valve as soon as you notice a leak.
- Open all faucets to drain the system and reduce pressure.
- Turn off electricity to affected rooms if it is safe.
- Move furniture and rugs out of the wet area.
- Take photos of the damage for your insurance records.
How the Pros Help After a Break
After a pipe breaks, the pros assess the water damage. They use moisture meters and thermal imaging to find hidden water in walls and under floors. Then they set up drying equipment, such as air movers and dehumidifiers, to pull moisture out of the building materials. The goal is to prevent mold and further structural damage.
The work usually involves removing soaked drywall, insulation, and flooring that cannot be saved. They also dry out the remaining structure and treat surfaces to discourage mold growth. The repair process can take several days depending on the size of the leak and the materials affected. Your insurance company may cover some of the costs, but policies vary, and your insurer decides what is covered.
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Call Now (703) 462-1739Frequently asked questions
At what temperature should I worry about my pipes freezing?
Worry when the outdoor temperature stays at or below 20 degrees Fahrenheit for several hours. However, poorly insulated or exposed pipes can freeze at 32 degrees if the cold air reaches them directly. A slow drip helps keep water moving and reduces the risk.
How long does it take for pipes to freeze at 20 degrees?
It depends on the pipe location, insulation, and water movement. An exposed pipe in an unheated garage can freeze within a few hours at 20 degrees. Pipes inside heated walls may take longer. Running a trickle of water can delay freezing significantly.
Can pipes freeze if the heat is on in the house?
Yes, if the heat does not reach every area. Pipes in exterior walls, crawl spaces, basements, or attics can still freeze even when the rest of the house is warm. Keep cabinet doors open and insulate pipes in those colder spots to reduce the risk.
More questions and answers
- Why Do Pipes in Exterior Walls Freeze More Easily?
- Why Do Pipes Freeze and Burst in Cold Weather?
- Which Pipes Are Most Likely to Freeze in Cold Climates?
- How Do I Prevent Pipes From Freezing in Winter?
- What Is Freeze-Drying for Water-Damaged Documents?
- What Parts of a Home Are Most at Risk From Frozen Pipes?
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