Pipes can take anywhere from about 30 minutes to many hours (or even days, if you just “wait on the weather”) to unfreeze, depending on how cold it is, where the pipe is, and how you thaw it.

Quick Scoop

For a typical frozen indoor water line, using safe heat (like a hair dryer or space heater nearby), many pros say you’re usually looking at roughly 30–45 minutes of active thawing time to get water moving again. But that’s only a rough average.

Key timing ranges:

  • Actively thawing an exposed indoor pipe: often 30–45 minutes with steady heat.
  • Enclosed pipes in walls/ceilings: can take hours , since the heat has to penetrate insulation and building materials.
  • Underground or exterior lines: may take many hours or may not thaw until the outdoor temperature rises significantly , sometimes days or weeks if the deep freeze continues.
  • Letting pipes “thaw on their own” with no added heat: there’s no fixed formula; in long cold snaps, some areas report pipes staying frozen for days or even months if conditions stay below freezing.

A real‑world example: one home services company notes it can take roughly 30–40 minutes of applying heat to thaw exposed pipes, while more hidden or underground lines can be an “extremely time‑consuming and labor‑intensive” job. An insurance guide similarly pegs many thawing methods at about 30–45 minutes, but stresses that weather, duration of freezing, and pipe location can stretch that out.

What really affects thaw time?

The answer to “how long for pipes to unfreeze” depends mainly on:

  • Location of the pipe
    • Exposed in a basement, crawlspace, or under a sink = faster.
    • Inside exterior walls, ceilings, or underground = much slower.
  • How cold it is outside
    • Pipes typically start freezing when temps drop to around 20°F (about −6°C), especially with poor insulation.
* If temps stay below freezing, pipes may not thaw at all without deliberate heating.
  • How long they’ve been frozen
    • A light freeze for a few hours often clears faster.
    • A pipe frozen all night or for multiple days can have a thicker ice plug that takes longer to melt.
  • Your thawing method
    • Constant, gentle heat (hair dryer, space heater in the room, heat tape used correctly) speeds things up.
* Just turning up the thermostat and waiting will usually be slower, especially for pipes inside walls.

Safety first: risks while you wait

The more time pipes stay frozen, the higher the risk they’ll burst as ice expands and pressure builds. The risk starts to climb after several hours of sustained freezing, and there’s no exact “burst at X hours” number—conditions matter a lot.

To lower the odds of damage while things thaw:

  1. Slightly open faucets on the frozen line so any melting water can trickle out and relieve pressure.
  1. If you suspect a burst (noisy bang, sudden loss of pressure, water stains), shut off the main water valve immediately.
  1. Use only safe heat sources: hair dryer, space heater placed away from combustibles, heat tape installed per instructions.
  1. Avoid open flames, torches, or boiling water on pipes; they’re major fire and damage hazards.

Typical expectations: a quick guide

Here’s a compact way to think about “how long for pipes to unfreeze” in common scenarios (assuming you’re using safe, active thawing):

  • Under‑sink pipe inside a heated house: ~30–60 minutes.
  • Basement or crawlspace pipe with good access: ~30–90 minutes.
  • Pipe inside an exterior wall: a few hours, sometimes longer, and may need a pro.
  • Exterior or yard service line: many hours to days, often professional‑only work.

Because weather patterns have been producing more sudden deep freezes in recent winters, frozen‑pipe questions have been trending in home‑repair blogs and Q&A sites every time a big cold front hits.

If your pipes are frozen right now

If you’re currently dealing with this:

  1. Turn up your home’s heat and open cabinet doors around sinks.
  2. Open the affected faucets slightly.
  3. Apply gentle, continuous heat to the accessible section of the pipe, moving slowly along its length.
  4. Stop and shut off water if you see leaks, bulges, or new water stains, and call a plumber or emergency service.

If nothing changes after a couple of hours of careful thawing, or you can’t access the frozen section, it’s time to bring in a professional, since hidden damage can be costly.

TL;DR: With active, safe heat, many indoor frozen pipes unfreeze in about 30–45 minutes, but hard‑to‑reach, deeply frozen, or outdoor lines can take many hours or even wait on a full weather warm‑up.

Information gathered from public forums or data available on the internet and portrayed here.