Unfreezing a drain pipe requires a balance of internal melting (using safe chemical reactions) and external warming (using gradual heat sources). Do not use open flames
like blowtorches, as they can damage PVC or copper and pose a severe fire risk. American Red Cross Internal Thawing: The "Saline & Fizz" Method
If the frozen section is deep inside the drain, use household ingredients to lower the freezing point of the ice. Anytime HVAC Step 1: Agitate the Ice. Pour 1/2 cup of baking soda down the drain, followed by 1 cup of white vinegar
. The resulting fizzing reaction helps break up the surface of the ice block. Step 2: Apply Salt. Mix 1 cup of kosher or rock salt how to unfreeze a drain pipe 2021
into a gallon of hot water (not boiling, to avoid cracking the pipe). Pour this "slurry" slowly down the drain; the salt lowers the freezing point of the ice, much like it does on sidewalks. Step 3: Repeat.
If the drain doesn't clear immediately, repeat the process. Avoid adding excessive water if the drain is completely blocked, as it may just freeze and worsen the clog. ICE Cleaning External Thawing: Safe Heat Application
If you can access the pipe (e.g., under a sink or in a crawl space), apply gradual external heat: American Red Cross Hair Dryer or Heat Gun: Unfreezing a drain pipe requires a balance of
Set to a low/medium setting and move it back and forth along the frozen section. Do not keep it in one spot for too long to avoid cracking the material. Hot Towels:
Soak towels in hot water, wring them out, and wrap them around the pipe. Replace them as they cool. Space Heater:
Position a portable heater near the pipe (at least 3 feet away) to warm the ambient air. Vital Safety Precautions Preventing & Thawing Frozen Pipes | American Red Cross Part 7: When to Call a Professional Plumber
Some freezes are beyond DIY. Call a licensed plumber immediately if:
Expected cost in 2021: Professional thawing and repair ranges from $200 to $600 depending on location and pipe material. Compare that to potential water damage (thousands of dollars) if a pipe bursts while you’re away.
This is critical. Always apply heat starting at the downstream side of the ice plug (closer to the main sewer or exit point) and work backward toward the fixture. Why? If you thaw the upstream side first, water will melt and then refreeze against the remaining ice plug, creating a worse dam.
If standing water is in the sink or tub, a shop vac is your best friend.