At What Temperature Do Pipes Freeze and Burst?
Last updated October 19, 2026
The short answer
The Critical Freezing Threshold
The general rule is that water inside pipes can freeze when the air temperature reaches 20 degrees Fahrenheit. This risk increases dramatically for extended periods of cold. Uninsulated pipes in vulnerable areas like attics, crawl spaces, and exterior walls are at risk even when the thermostat inside is set much higher.
Wind chill and sustained sub-freezing temperatures accelerate the process. A single cold night might not cause a problem, but consecutive nights below 20 degrees Fahrenheit greatly increase the likelihood of frozen pipes. Your home's specific insulation and exposure to wind drafts also play a major role in determining the actual risk temperature for your plumbing.
How Frozen Pipes Lead to Bursts
A pipe does not typically burst at the point where the ice forms. Instead, water pressure builds between the ice blockage and a closed faucet. As the ice expands and water cannot flow, the pressure inside the pipe rises to a point where the pipe material fails, often at a weak joint or section.
The burst usually happens downstream from the ice blockage. This is why you might not notice a problem until the ice thaws and water begins to flow again, releasing a flood from the rupture. This is also why simply thawing a frozen pipe can be dangerous if you do not first shut off the water supply.
- Ice forms and blocks the flow of water.
- Water pressure builds between the ice and a closed valve.
- Pressure exceeds the strength of the pipe material.
- A rupture occurs, often at a seam or joint.
- Damage may remain hidden until the ice melts.
- The subsequent water release can be sudden and severe.
Identifying Your Home's Vulnerable Pipes
Some pipes are far more susceptible to freezing. Common trouble spots include supply lines running through uninsulated exterior walls, pipes in unheated garages or basements, and outdoor hose bibs. Plumbing in attics or crawl spaces is especially vulnerable, as these areas often have little to no heat and poor insulation.
You can inspect these areas before the start of the cold season. Look for gaps where cold air can enter, such as around dryer vents or cable entries. Check the insulation on pipes, especially where they enter the home from outside. Even occasional hard freezes can affect these vulnerable spots.
Immediate Steps After a Pipe Bursts
Your first action must be to stop the flow of water. Locate your home's main water shutoff valve and turn it off immediately. If you cannot find it or it is stuck, call a plumber. Then, turn off electricity to the affected area at the circuit breaker if it is safe to do so, to prevent shock hazards.
After securing safety, move any furniture or valuables away from the water. Use towels to soak up standing water, but understand this is only a temporary measure. The water needs to be extracted and the area dried quickly to prevent secondary damage like mold growth and structural decay.
- Shut off the main water supply valve.
- Turn off electricity to the wet area if safe.
- Move furniture and belongings to a dry area.
- Remove excess water with a mop or towels.
- Contact a local plumber for pipe repair.
- Contact local water damage pros for cleanup.
Professional Water Damage Mitigation
Once the water is off, the cleanup process is critical. Water damage pros use industrial extractors to remove hundreds of gallons quickly. They then set up high-powered air movers and dehumidifiers to dry the structure thoroughly, including inside walls and under flooring. This process, called structural drying, aims to restore your home to a dry standard.
Without professional drying, hidden moisture can lead to mold within 24 to 48 hours. The pros use moisture meters and thermal imaging to detect water you cannot see. Their goal is to prevent long-term damage and costly repairs. Policies vary, and your insurer decides what is covered.
Talk to someone now
Phones are answered 24/7 for DeSoto and nearby communities.
Call Now (469) 209-4452Frequently asked questions
At what temperature should I start dripping my faucets?
Start dripping faucets when outside temperatures are forecast to drop below 20 degrees Fahrenheit, especially for an extended period. A slow, steady drip from both hot and cold lines relieves pressure inside the pipes and helps prevent ice blockages from forming.
How can I prevent my pipes from freezing?
Insulate exposed pipes with foam sleeves, especially in attics and crawl spaces. Seal air leaks near pipes with caulk or spray foam. Keep cabinet doors open to allow warm air to circulate. Disconnect and drain outdoor hoses, and consider installing frost-proof hose bibs.
What should I do if I discover a frozen pipe?
Keep the faucet open. Gently apply heat to the frozen section using a hair dryer, heat lamp, or towels soaked in warm water. Never use an open flame. If you cannot locate the freeze or thaw it, call a plumber immediately to prevent a potential burst.