How to Unfreeze Water Pipes

Water can freeze in home pipes due to faulty taping, a malfunctioning thermostat, or inadequate insulation. Worse, the frozen water can rupture the pipe and cause major damage. Start by looking for cracks and split pipes, and locate the main shut-off valve so you can prevent a flood if necessary. If you've avoided this fate, apply mild heat or insulation to thaw the pipes.

EditSteps

EditLocating the Frozen Pipe

1. Narrow down the search. Turn on all faucets to see which ones are working. If water is running through one faucet but not another, the problem is located along the pipes running between the two. Leave all faucets open slightly. A small trickle of running water from working faucets can prevent further freezing and help melt the ice. Leave blocked faucets open as well to reduce pressure on the pipes.
   
   • Most American houses have faucets on external walls too, especially on the front and back of the house.
2. Look in the most likely areas. If a large area of your house has no water, look in the most likely and accessible areas first before you start tearing apart walls. Use the steps below to focus on these areas, unless you managed to narrow down the search to a smaller portion of your house:
   
   • Pipes in or near uninsulated crawlspaces, attics, or basements.
   • Pipes near cold air vents or cold concrete.
   • Outdoor valves and spigots.
   • Outdoor pipes can freeze, but check these last, as most systems are designed to keep standing water out of these pipes.
3. Search for cracks and leaks. Examine the pipes in the affected area carefully. Freezing water can cause pipes to crack from the change in pressure, usually splitting the pipe lengthwise or causing cracks in the joints.
   
   • To look at the backs of pipes near walls, and in other difficult to reach areas, use a flashlight and a large dental mirror from a hardware store.
   • If you find a leak, close the main shut-off valve immediately. Call a plumber to replace the pipe, or fix it yourself if you are up to the task.
4. Find the frozen area. Assuming there are no leaks or cracks, find the section of the pipe with frozen water using one of the following methods.
   
   • Feel the temperature of the pipe with your hand, or use an infrared thermometer to locate areas significantly colder than other pipes.
   • Tap the pipe with a screwdriver handle or other object, listening for a more solid, less "hollow" sound.
   • If you rule out all exposed pipes in the affected area, skip to the section on unfreezing pipes inside walls.

EditUnfreezing Water Pipes

1. Leave faucets slightly open. Open the faucet attached to the frozen pipe, and open nearby working faucets to a trickle. Running water is much less likely to freeze than standing water. If the running water passes through or near a frozen area, it may even help thaw the ice over the course of an hour or two.
   
   • If you see any cracks in any pipe, turn off the main water supply to your house immediately, and close all faucets.
2. Use a hair dryer or heat gun. Turn on a hair dryer and run it back and forth along the frozen pipe. Keep it moving and do not place the dryer directly against the pipe, as uneven or sudden heating can rupture the pipe. If your pipes are metal, you can use a more powerful heat gun in the same fashion.
   
   • PVC pipes can be damaged at temperatures as low as 140ºF (60ºC). Never use a heat gun or other direct heat stronger than a hair dryer.
   • Outdoor valves often have fiber washers or other non-heat-safe materials inside them. Heat them slowly and cautiously.
3. Apply heat tape. Purchase electrical heat tape from a hardware store. Wrap the tape in a single layer around the length of the frozen pipe, then plug it into a power source. The tape consists of heating elements that warm up when turned on.
   
   • Do not overlap electrical heat tape. Wrap it around the pipe only once or in a spiral pattern.
4. Heat the surrounding air. Position space heaters, bare incandescent light bulbs, or heat lamps in the room with the frozen pipe, near the pipe but not touching it. Hang up tarps or blankets to trap the heat in a smaller area, but don't let them come into direct contact with the heat source. For large rooms, use several heat sources to ensure safe, even heating of the pipe.
   
5. Add salt to frozen drains. Salt lowers the melting point of ice, causing it to melt at colder temperatures. Pour a tablespoon (15 mL) of salt down the drain, and give it time to act on the ice.
   
   • You can try dissolving the salt in 1/2 cup (120 mL) boiling water first, but this risks bursting the pipe with a sudden temperature change.^[1]
6. Wrap the pipe in hot towels. Put on rubber gloves, and soak towels in hot water. Ring them out, then wrap them securely around the frozen section of pipe. Replace with freshly soaked, hot towels every 5–10 minutes until the pipe thaws.
   
   • Do not leave cold wet towels around the pipes.

EditThawing Pipes inside Walls

1. Blow a fan heater into outdoor vents. If you can find an external vent, put down a fan heater blowing warm air into the vent. Use a cardboard box or tarp to minimize the amount of heat lost to the surrounding air.
   
2. Turn up the central heating. Crank the heat in the house to around 75 to 80ºF (24–27ºC) and wait two to three hours.
   
   • Open closet and cabinet doors so the warm air circulates as close to the walls as possible.
3. Cut a hole in the wall. Unfortunately, this is often necessary to reach a frozen pipe before it bursts. Follow the instructions in the locating pipes section to isolate the most likely area of the problem. Use a keyhole saw to cut a hole into this area, then use any of the methods in the section on unfreezing pipes.
   
   • If this is a recurring problem, consider installing a cabinet door over the hole instead of fully repairing the wall, for ease of access next time this occurs.

EditPreventing Frozen Pipes

1. Insulate the pipes. Keep pipes in cold areas wrapped with "pipe sponge" covers, rags, or other insulating material. If an electrical outlet is nearby, you can keep them wrapped with electrical heat tape, unplugged, then plug the tape in whenever cold weather arrives.
   
2. Protect the pipes from wind and cold air. Check your crawlspaces and external walls for holes, and repair them to minimize exposure to cold air. Use wind barriers or faucet covers to protect faucets and valves on the exterior of the house.
   
3. Heat the area. During cold weather, turn on a 60 watt incandescent light bulb near the area of pipe that previously froze, or just below it. If used to warm crawl spaces and other unsupervised areas, make sure there are no flammable materials kept in the same space.
   
4. Leave a trickle of water running. It is much more difficult for pipes to freeze if water is running through them, since the water will usually travel through the pipe before it has time to freeze. During sub-freezing weather, keep faucets slightly open to allow a trickle of water.
   
   • You can adjust the ballast in your toilet tank to keep it running even when the tank is full.

EditTips

• If the weather is expected to warm up within a day, using bottled water until then can be more cost-effective than using new tools and energy to thaw the pipes.

EditWarnings

• Do not break through drywall unless you are sure of the location of the frozen pipe.
• Never pour drain cleaner or other chemicals down your frozen pipe, as they can burst the pipe by creating too much gas or heat. A small amount of hot water can be used as a last resort, but even this is risky.
• Never use a torch to heat a frozen pipe. You can destroy the pipe and cause a fire.
• Always work in a dry environment when utilizing electrical equipment.

EditThings You'll Need

• Infrared thermometer
• Hair dryer
• Heat gun
• Rags
• Water
• Electrical heat tape
• Keyhole saw
• Space heater

EditRelated wikiHows

• Defrost Water Pipes That Have Been Frozen
• Prevent Frozen Water Pipes
• Clear a Clogged Drain with Vinegar
• Wrap Pipes for Cold Weather

EditSources and Citations

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