Winter weather can be beautiful, but it can also cause serious problems inside your home. One of the most common and expensive winter plumbing issues is frozen pipes. When pipes freeze, they can burst and release large amounts of water into your home.
Many homeowners believe pipes burst because ice expands inside them. While this is partly true, the real reason is pressure buildup inside the pipe. Understanding how frozen pipes burst and learning simple prevention steps can save you thousands of dollars in repairs.
According to This Old House plumbing expert Richard Trethewey, freezing water has enough force to break even strong metal pipes. That is why cold-weather preparation is so important.
This guide explains everything you need to know about frozen pipes, including how they burst, warning signs, prevention tips, and what to do in an emergency.
What Happens When Pipes Freeze?
Water changes when it freezes. Instead of staying liquid, it turns into ice and expands. This expansion starts a chain reaction inside your plumbing system.
Here is what happens step by step:
- Cold air reaches the pipe
- Water inside the pipe begins to freeze
- Ice forms a blockage
- Pressure builds behind the ice
- The pipe cracks or bursts
Most people think pipes break where ice forms. In reality, pipes usually burst in a nearby section where pressure becomes trapped.
The Science Behind Frozen Pipes
When water freezes, it expands by about 9 percent. This might not sound like much, but inside a closed pipe, it creates extreme pressure.
Pressure Buildup Inside the Pipe
As ice blocks part of the pipe, water becomes trapped between the blockage and a closed faucet or valve. When more water freezes, pressure keeps increasing.
This pressure can reach up to 25,000 pounds per square inch (PSI). Most household pipes are only designed to handle a small fraction of that pressure.
Why Pipes Eventually Break
Pipes have weak spots such as joints, bends, or older sections. When pressure rises too high, these weak areas split open. The crack may be small, but once the ice melts, water can pour out quickly.
Which Pipes Are Most at Risk?
Some pipes are more likely to freeze than others:
- Pipes in unheated areas (basements, attics, garages)
- Pipes near exterior walls
- Outdoor faucets and hose bibs
- Pipes in crawl spaces
- Older plumbing systems
If your home has any of these, extra protection is necessary.
What Damage Can a Burst Pipe Cause?
A burst pipe can cause major damage in a short amount of time.
Immediate Water Damage
Once a pipe bursts and thaws, water can flood floors, walls, ceilings, and furniture. Even a small crack can release hundreds of gallons of water in a few hours.
Electrical Hazards
Water near electrical outlets or appliances can cause shocks or fires. This makes burst pipes dangerous, not just messy.
Mold and Mildew Growth
Moisture inside walls and floors creates perfect conditions for mold. Mold can spread quickly and affect indoor air quality.
Structural Damage
Long-term water exposure weakens wood, drywall, and insulation. This can lead to sagging floors, cracked walls, and costly repairs.
Common Signs of Frozen Pipes
Knowing the warning signs can help you act before a pipe bursts.
- Little or no water from faucet
- Frost on exposed pipes
- Strange noises when turning on water
- Bulging or cracked pipe sections
- Bad smells from drains
If you notice any of these signs, take action immediately.
How to Prevent Frozen Pipes
Prevention is easier and cheaper than repairs.
Insulate Your Pipes
Use foam pipe insulation or heat tape on exposed pipes. Focus on:
- Basements
- Attics
- Crawl spaces
- Under sinks
- Garage walls
Seal Air Leaks
Cold air entering through gaps can freeze pipes. Seal cracks around:
- Windows
- Doors
- Vents
- Where pipes enter walls
Use caulk or weather stripping.
Keep Your Home Warm
Even if you are away, keep the thermostat set to at least 55°F (13°C). Open interior doors to allow warm air to circulate.
Let Faucets Drip
During very cold nights, let one or two faucets drip slightly. Moving water is less likely to freeze and helps relieve pressure.
Open Cabinet Doors
Open cabinets under sinks to allow warm air to reach plumbing.
Drain Outdoor Plumbing
Disconnect garden hoses and drain outdoor faucets before winter begins. Use insulated faucet covers for extra protection.
What to Do If Your Pipes Freeze
If you believe a pipe is frozen, act carefully.
Step 1: Locate the Frozen Area
Look for frost, bulging, or extremely cold sections of pipe.
Step 2: Turn On the Faucet
Open the faucet connected to the frozen pipe. This allows water to escape once thawing begins.
Step 3: Apply Heat Safely
Use one of these methods:
- Hair dryer
- Heating pad
- Warm towels
- Portable space heater (from a safe distance)
Start heating near the faucet and move toward the frozen section.
Step 4: Never Use Open Flames
Do NOT use torches, candles, or open flames. These can damage pipes and start fires.
What to Do If a Pipe Bursts
Quick action can limit damage.
Shut Off the Water
Find your main water shutoff valve and turn it clockwise to stop the flow.
Turn Off Electricity (If Needed)
If water is near electrical outlets, turn off power at the breaker box.
Call a Plumber
Contact a licensed plumber immediately for repairs.
Remove Standing Water
Use towels, mops, or a wet/dry vacuum.
Document the Damage
Take photos and videos for insurance claims.
Long-Term Prevention Tips
- Schedule yearly plumbing inspections
- Upgrade old pipes
- Install smart leak detectors
- Add extra insulation in cold areas
- Keep garage doors closed
These steps provide extra protection year after year.
How Long Does It Take for Pipes to Freeze?
Pipes can freeze in as little as 6 hours when temperatures drop below 20°F (-6°C). Wind and lack of insulation can make freezing happen even faster.
Can Frozen Pipes Thaw on Their Own?
Sometimes, but it is risky. When ice melts suddenly, pressure can cause bursting. It is safer to thaw pipes slowly using controlled heat.
Should You Call a Plumber for Frozen Pipes?
Call a plumber if:
- You cannot locate the frozen area
- Pipes are already cracked
- You feel unsure about thawing safely
Professional help can prevent bigger problems.
Frequently Asked Questions (FAQ)
Can PVC pipes freeze?
Yes. Plastic pipes can freeze and burst just like metal ones.
Is heat tape safe?
Yes, if installed correctly and used according to instructions.
Should I turn off water when leaving home?
Yes. If traveling in winter, shut off water and drain pipes.
Are newer homes immune to frozen pipes?
No. Any home can experience frozen pipes without proper insulation.
Final Thoughts
Frozen pipes are one of the most common winter home disasters. The good news is that they are largely preventable. With insulation, proper heating, and simple maintenance, you can greatly reduce your risk.
Taking time now to protect your plumbing can save you from expensive repairs, water damage, and stress later.
If you are unsure about your plumbing system, schedule a professional inspection before winter arrives. A little preparation today can protect your home for years to come.