Having frozen pipes can be a major inconvenience, leaving you without running water until they thaw. The amount of time it takes for pipes to unfreeze depends on several factors, including the temperature, pipe material and size, and what actions you take to speed up the process. With some effort, you can get your pipes unfrozen in as little as a few hours in mild freezes. However, it can take over a day if temperatures are extremely cold.
What Causes Pipes to Freeze?
Pipes freeze when the water inside reaches 32°F or below. This is because water expands as it freezes, putting pressure on the pipes until they burst. Pipes are most likely to freeze when exposed to cold air, such as those located:
- In uninsulated exterior walls
- In unheated areas like attics, crawl spaces or garages
- Near drafts from doors, windows or vents
Smaller pipes freeze more quickly than larger ones since they contain less water volume. Copper and plastic pipes freeze faster than PVC or PEX. Pipes with water flow are less prone to freezing than stagnant water pipes.
Prolonged freezing temperatures below 20°F put pipes at high risk of freezing. Factors like poor insulation, thermostat issues, a broken window or open door can also cause indoor temperatures to drop low enough to freeze pipes.
Signs Your Pipes Are Frozen
The most obvious sign of frozen pipes is a loss of water flow from faucets and fixtures. You may also hear odd noises like banging or cracking as the pipes expand and contract.
Check your home for these other signs of frozen pipes:
- Very low water pressure
- No water comes out of hot water faucets
- Toilets won’t flush
Feel your pipes – frozen sections may feel much colder than others. Shine a flashlight along accessible pipes to check for ice blockages.
If you confirm you have frozen pipes, shut off the water at the main valve to avoid major flooding risks when the ice melts.
How Long It Takes for Pipes to Unfreeze
Several key factors affect how long it takes for frozen pipes to thaw:
Outside Temperature
The colder it is outdoors, the longer pipes will take to thaw. At milder temperatures above 30°F, pipes may unfreeze within 3-6 hours. But at subzero temperatures, it can take over a day:
| Outside Temperature | Estimated Time to Unfreeze |
|---|---|
| 30°F to 15°F | 3 to 6 hours |
| 15°F to 0°F | 6 to 12 hours |
| 0°F to -15°F | 12 to 24 hours |
| Below -15°F | Over 24 hours |
At below freezing temperatures, it’s crucial to use active thawing techniques and not just wait for pipes to unthaw over time.
Pipe Size and Location
Smaller diameter pipes freeze more quickly as they contain less water volume. Half-inch or 3/4 inch supply lines serving individual fixtures tend to freeze sooner than 1 inch or larger main lines.
Pipes positioned against exterior walls or in unheated areas will also freeze faster than indoor plumbing with heat exposure.
Pipe Material
Some materials retain heat better and are more resistant to freezing:
- Plastic: Freezes most readily. PVC and CPVC pipes freeze faster than polyethylene (PEX).
- Copper: Quick to lose heat and freeze. Small diameter copper pipe especially prone.
- PEX: More freeze resistant than copper or rigid plastic.
- Cast Iron: Older iron pipes freeze slowly due to thickness.
Flowing vs. Stagnant Water
Pipes containing flowing water from regular use take longer to freeze than stagnant pipes with standing water. Stagnant water located against exterior walls or in unheated areas will freeze quickest.
Pipe Insulation
Insulated pipes won’t freeze as readily and will thaw faster than non-insulated pipes. Foam, fiberglass or rubber insulation slows heat loss. If possible, wrapping pipes in high-risk areas can help prevent freezing altogether.
Thawing Frozen Pipes
If your pipes do freeze, you can use various methods to safely thaw them:
Open Indoor Faucets
Keep water trickling from an indoor faucet closest to where pipes are likely frozen. This introduces warmer indoor air and relieves pressure in the pipes via the open tap.
Direct Heat
Apply gentle, direct heat along the frozen section of pipe using a hair dryer, space heater or hot water. Avoid open flames. Wrap pipes in rags or towels to absorb condensation as ice melts.
Circulating Heat
Place a space heater or heat lamp near frozen pipes to warm the area and radiate heat. Never leave portable heaters unattended.
Emergency Plumbing
As a last resort if pipes are badly frozen, call a plumber to safely thaw pipes with professional equipment.
Increase Room Temperature
Raise the thermostat temperature in areas where pipes are frozen to warm the environment.
Heat Tape/Cable
Outdoor pipes prone to freezing can be wrapped in electric heat tape or heat cable to maintain temperature above 32°F. These are turned on during freezing weather.
Tips to Prevent Frozen Pipes
It’s much easier to prevent frozen pipes than dealing with the aftermath. Try these proactive measures before cold weather sets in:
- Insulate pipes in unheated areas like attics, garages or crawl spaces.
- Seal leaks and cracks in walls, doors, windows or foundations.
- Disconnect outdoor hoses and shut off and drain water to outdoor faucets.
- Open cabinet doors to allow warm air to reach pipes under sinks.
- Allow faucets to drip during sub-freezing weather.
- Keep thermostat set above 55°F even when away.
Conclusion
Frozen pipes are inconvenient but can usually be thawed safely in less than a day. The amount of time depends on outside temperature, pipe size and location, water flow, and pipe material. Actively applying heat speeds the thawing process. Above all, prevention is key – insulating vulnerable pipes and maintaining adequate heat through winter can help avoid frozen pipe headaches altogether. With some preparation, you can get through winter without your pipes turning into icicles!
