Before applying any heat, follow these safety steps to prevent water damage:

Only use UL-listed tape designed for drains (not supply lines). Wrap spirally around trap and pipe. Plug into GFCI.

For drains that are inaccessible, such as those behind walls or underground, the most effective tool is often a plumbing snake or auger equipped with a hot water attachment. While this is often best left to professionals, resourceful homeowners can sometimes utilize a standard drain snake to break through the ice. By feeding the snake into the drain and rotating it, the tip can bore a small hole through the ice. Once a channel is opened, even a small one, hot water can be poured down to melt the remaining ice walls from the inside out.

Start with warm air and patience. Most frozen drains thaw within 1–2 hours with a hair dryer or space heater. If not, call a plumber before the pipe bursts. Prevention (insulation, heat tape, cabinet doors) is far cheaper than a flooded basement.

Check unheated areas like basements, crawl spaces, and attics. Look for frost on the pipe or a slight bulge in the material.