Thawing a frozen pipe safely means applying heat gradually, working from the faucet back toward the frozen section, and keeping the faucet open so water and steam can escape as the ice melts. The most dangerous mistake homeowners make is using an open flame — propane torches, heat guns set to maximum, or anything that concentrates intense heat on a single spot risks both a pipe rupture and a fire inside a wall cavity. Safe thawing is slow and controlled. If you can’t locate the frozen section or access it safely, calling a plumber is the right call.

Before You Start: Check for Bursts First

Before applying any heat, look carefully at every visible section of the frozen pipe for cracks, splits, or obvious bulges. Ice expands as it freezes and can split copper or plastic pipe — a pipe that looks intact while frozen may release a significant flow once the ice melts. If you see any signs of damage, shut off the main water supply before thawing and call for emergency plumbing service. Trying to thaw a burst pipe without shutting off water first turns a plumbing problem into a water damage disaster.

Also open the faucet on the affected line before you start. You want somewhere for the water to flow as the ice thaws, and the open faucet lets you monitor progress — you’ll see a trickle, then normal flow, as the blockage clears.

Safe Methods for Thawing Exposed Pipes

For pipes you can see and reach — under a sink, in a crawl space, along a basement wall — these methods work safely:

  • Hair dryer on low or medium heat: Start at the faucet end and work back toward the frozen section. Keep the dryer moving rather than holding it in one spot. This is the most commonly recommended approach for accessible pipes.
  • Electric heating pad or heat tape: Wrap around the frozen section and plug in. Self-regulating heat tape is especially good for this — it adjusts its heat output to avoid overheating.
  • Hot towels: Soak towels in hot water and wrap them around the pipe, refreshing them as they cool. Slower than a dryer but effective for short frozen sections.
  • Portable electric space heater: Positioned to warm the air around the pipe in an enclosed space like a cabinet or crawl space. Safe if kept away from moisture and flammable materials.

What Never to Use

Avoid open flames of any kind — propane torches, butane lighters, candles. These can superheat a section of pipe, causing it to burst, and can ignite insulation or framing inside wall cavities before you ever see smoke. A wall fire that starts behind drywall can burn for a significant time before it becomes visible. Blowtorch-caused house fires from attempted pipe thawing are a real and well-documented risk. Also avoid high-heat setting on heat guns — the same concern applies. Slow, even, moderate heat is what works safely.

When the Frozen Section Is Inside a Wall

This is the scenario where DIY has real limits. If the frozen pipe runs inside a finished wall, you can try turning up the heat in the room, opening cabinet doors on the same wall, and waiting — sometimes the ambient warmth thaws the line on its own. An infrared space heater aimed at the wall can help speed this. But if the section doesn’t thaw within a reasonable time (a couple of hours), or if you’re worried about a possible burst, a plumber with specialized thawing equipment can locate and address the freeze without tearing into the wall unnecessarily.

After Thawing: Prevent It From Happening Again

Once the water is flowing again, take a few minutes to understand why that section froze. Was the heat setback too aggressive? Is the pipe run along an exterior wall without insulation? Is there a gap in the building envelope letting cold air into the crawl space? Identifying the cause lets you address it before the next cold snap. Common fixes include adding foam pipe insulation, sealing air gaps around penetrations, or installing heat tape on vulnerable runs. Colorado winters bring multiple sub-zero events most years — a pipe that froze once is likely to freeze again if the underlying condition isn’t addressed.

Done handles emergency plumbing including frozen and burst pipe situations throughout the Denver metro. For pipe repair, insulation, or a pre-winter plumbing assessment, visit our pipes and lines page or contact Done to schedule service.