How to Safely Thaw Water Pipes Under the House

Frozen pipes can burst if not thawed properly.

One of the dangers homeowners in cold climates face is frozen water pipes. Frozen pipes don't simply mean the loss of running water for a time -- expanding ice can burst even iron or steel water pipes, causing both expensive plumbing repairs and potentially severe water damage. To combat frozen pipes, homeowners must be aware of the dangers involved while thawing pipes and take precautions to prevent plumbing damage.

Things You'll Need

• Hair dryer or portable heater
• Rags or heating pad (optional)

Instructions

1. Identify which pipes are frozen by opening each of your home's faucets and noting which ones do not work, or work only very slowly (indicating a partial freeze). You can also identify frozen pipes by touch, with frozen ones noticeably colder than those that are flowing.

2. Open the faucets that are serviced by the frozen pipe(s) to accommodate draining the melting water. Free-flowing water will alert you when you've successfully thawed the pipes, and slowly flowing water may help to melt the existing blockage.

3. Start with the portion of the frozen pipe that's closest to the open faucet and apply radiant heat from a hair dryer or space heater to the pipe. Keep the heat source moving so that the heat is applied evenly along the length of the obstruction. Alternately, you can also apply heat by wrapping the pipe in rags soaked in hot water or a water-resistant heating pad set on its lowest setting.

4. Heat inaccessible pipes by raising the ambient temperature around them. Pipes concealed by walls or flooring can be heated by applying heat via a portable heater to the area, leaving at least 18 inches between the heat source and the wall or floor.

5. Close the affected faucets when full water flow has returned to the pipe.

Tips & Warnings

• Do not use a direct flame or boiling water to heat frozen pipes. Heating frozen pipes too quickly may crack, split or burst the affected pipe, causing leaks and/or injuries. What's more, use of an open flame risks causing a fire.

• Once the frozen pipe has been thawed, investigate the reason why the pipe froze and address any exposure to cold that you find with additional insulation or expanding foam.

• When using a portable heater, be sure that all flammable objects have been removed from an area before exposing it to heat.

References

• Plumbing Networks: How to Thaw Frozen Pipes
• 411 Plumb: How to Avoid and Thaw Frozen Pipes Safely
• ACME How To: How To Thaw Frozen Pipes
• Gomestic: What You Can Do If Your Water Pipes Freeze Up