Frozen Pipes: What to Do Right Now

Frozen pipes in Seattle are most common during the region’s periodic hard cold snaps — nights that drop into the teens or below, especially after extended mild weather that left pipes unprotected. If you’ve turned on a faucet and nothing comes out, or if you’re seeing very low pressure from specific fixtures, a frozen pipe is likely. Here’s what to do, in order.

How to Thaw Frozen Pipes Without a Plumber

Locate the frozen section: The most likely frozen locations:
– Pipes in uninsulated exterior walls (kitchen sink on exterior wall, bathroom against garage)
– Pipes in the crawl space — especially if vents are open
– Pipes in a garage that runs through or near the garage
– Supply lines to an outdoor hose bib that’s not frost-free

If you can access the pipe directly:

Hair dryer: The safest and most controllable method. Apply heat slowly, starting from the faucet end of the pipe and working back toward the colder area. Keep the faucet open so water and steam can escape as the ice melts.

Electric heating pad or heat tape: Wrap around the pipe. Safe for plastic and copper; use low or medium setting.

Hot towels: Soak towels in hot water and wrap around the pipe. Works but requires frequent replacement as the towels cool.

Space heater: Directing a space heater at the area around the pipe (in a crawl space or utility room) warms the ambient air and thaws the pipe indirectly.

What NOT to use:
– Open flame (propane torch, lighter) — fire risk and can damage pipe fittings
– Boiling water poured directly on pipes — thermal shock can crack copper or PVC
– Any heating method left unattended

If you cannot access the frozen section:
Turn up the heat in the house, open cabinet doors under the affected sink to allow warm air circulation, and wait. If the pipe doesn’t thaw within 30–60 minutes or you suspect it may have burst, shut off the main water and call a plumber.

Frozen Pipes No Water — What to Do

Step 1: Check multiple fixtures. If only one faucet has no water, the freeze is localized to that branch. If no fixtures have water, the freeze may be in the main service line or a main supply branch.

Step 2: Check the water meter. If the meter shows no flow, the freeze is in the service line between the meter and the house, or in a main supply. If the meter shows flow but no water at the fixture, the freeze is inside the house.

Step 3: Identify the likely freeze location. For no water at a single fixture — trace the supply pipe back from the fixture toward the main, identifying where it passes through exterior walls, unheated spaces, or the crawl space.

Step 4: Apply heat to the suspected frozen section using the methods above.

Step 5: If you can’t find or access the frozen section, keep warm air circulating inside the house and call a plumber. A plumber can use specialized thawing equipment that circulates warm water or uses electrical current to thaw pipes in inaccessible locations.

Will Frozen Pipes Burst If I Turn the Heat On?

“Turning the heat on” (increasing the thermostat) is generally safe. Warming the house slowly thaws the pipe slowly — this is the preferred approach. Ice melts over time as heat penetrates to the pipe.

The concern: The risk of burst is highest when the pipe is frozen solid — the pressure is already at maximum. Rapid thawing using intense localized heat (like a torch) creates steam pressure inside the pipe that can cause failure. Gentle heat (thermostat increase, hair dryer, heating pad) doesn’t create this steam pressure.

The burst-when-thawing myth: Pipes don’t preferentially burst when thawing. The myth comes from the observation that homeowners often discover a burst pipe after thawing — but the pipe burst when it froze, not when it thawed. The damage was done during the freeze; the leak becomes apparent when water flows again after thawing.

The practical advice: Turn up the heat. Open cabinet doors under sinks. Apply a hair dryer to accessible frozen sections. These actions safely thaw the pipe without creating additional risk.

How to Tell If Your Pipes Are Frozen

No water from specific faucets: Turn on the cold faucet. If no water comes out (or just a trickle), the supply to that fixture is frozen.

Visible frost on accessible pipes: In a crawl space or utility room, frost on the outside of a pipe indicates the pipe contents are frozen.

Pipe feels abnormally cold: Touch accessible pipes. A pipe that’s significantly colder than expected on an already-cold day is more likely frozen. Copper or steel pipes transfer cold temperatures to the surface readily.

Recent extreme cold + unprotected location: If the temperature dropped to 20°F or below overnight and you have pipes in uninsulated spaces (crawl space with open vents, exterior wall kitchen sink, garage), assume those sections may be frozen before you even see symptoms.

Unusual sounds: A partially frozen pipe may produce gurgling, cracking, or no sound at all when a faucet is opened. Complete ice blockage is silent.

Frozen Pipe Thawed But Still No Water

If the pipe has thawed (confirmed: the pipe is no longer frozen) but there’s still no water:

Check if it truly thawed: Confirm by feel — the pipe should be at normal temperature, not still very cold. If sections in the crawl space or wall are still frozen, additional thawing is needed.

Burst pipe: If the pipe burst during freezing, water won’t flow through the break — it exits at the break point rather than continuing to the fixture. Look for: wet areas, drips from a ceiling or wall, water in the crawl space.

Air lock: Occasionally, a void left by the ice creates an air lock that prevents water flow even after thawing. Opening multiple faucets simultaneously sometimes resolves this.

Main valve partially closed: During a freeze event, if someone partially closed the main to limit damage, reopening it fully restores pressure.

Downstream freeze: In a system with multiple branches, one section may have thawed while another further downstream remains frozen — check the next section toward the fixture.

What Temperature Do Pipes Freeze?

The threshold: Water freezes at 32°F (0°C). Pipes typically start freezing when the pipe temperature drops to 32°F — which requires the surrounding air temperature to be below 32°F for long enough to chill the pipe contents.

Practical freeze threshold for home pipes:
– Above 20°F: Most pipes in protected locations are fine
– 15–20°F: Pipes in uninsulated crawl spaces and exterior walls begin to be at risk
– Below 15°F: Extended exposure at these temperatures freezes pipes in vulnerable locations with high reliability

Seattle context: Seattle temperatures rarely drop below 20°F. When they do — during the region’s occasional hard cold snaps — pipes in crawl spaces, exterior walls, and garage plumbing are the primary concerns. Pipes buried below 12–18 inches (below frost depth) are generally safe.

Duration matters: A pipe at 28°F for two hours is much safer than a pipe at 28°F for 12 hours. Overnight temperatures that dip just below freezing typically don’t cause freeze damage in Seattle’s housing stock.

How Long Does It Take for Pipes to Freeze?

Variables that determine freeze time:
– Pipe location (exterior wall vs. interior, insulated vs. uninsulated)
– Ambient temperature (more extreme = faster)
– Pipe contents (flowing water freezes more slowly than standing water)
– Pipe size (smaller diameter freezes faster)
– Insulation level

General Seattle estimates:
– Uninsulated pipe in a crawl space at 20°F: may freeze in 6–12 hours overnight
– Insulated pipe in a crawl space: significantly longer; may not freeze at all at 20°F
– Pipe in an exterior wall with no insulation: freezes with the wall temperature, potentially in 3–6 hours at 15°F
– Pipe under a kitchen sink on an exterior cabinet: slower — cabinet interior is warmer than the wall, but still at risk during extended cold

Frozen Pipes Under Kitchen Sink

Why kitchen sinks freeze:
– Kitchen sinks on exterior walls have supply pipes that run through the exterior wall cavity
– Cabinet doors kept closed prevent warm kitchen air from reaching the space under the sink
– If the exterior wall has minimal insulation, the pipe temperature tracks close to outdoor air temperature during cold snaps

Thawing:
1. Open the cabinet doors under the sink — allow warm room air to circulate
2. Apply a hair dryer to the pipes under the sink, particularly where they pass through the exterior wall (may not be visible — aim at the wall area)
3. Leave the hot and cold faucets both open — flowing water thaws faster, and steam can escape
4. A small portable space heater pointed at the open cabinet (with supervision) warms the cabinet interior effectively

Prevention going forward:
– Keep cabinet doors open during cold snaps
– Install pipe insulation on the supply pipes under the sink
– Add foam weatherstripping inside the cabinet against the exterior wall to reduce cold air infiltration

Can Frozen Pipes Unthaw on Their Own?

Yes — if temperatures rise above freezing.

If outdoor temperatures rise during the day and the pipe is in a location that warms as the house heats up, the pipe will thaw on its own over several hours. This is the passive approach — no action required.

Risks of waiting:
– If the pipe has already burst, water will flow when it thaws — possibly a significant leak
– If temperatures remain below freezing, the pipe stays frozen
– Pipes that freeze repeatedly experience increasing stress and eventual failure

What to do while waiting:
– Keep a faucet partially open on the frozen branch so water (and steam) can escape when thawing begins
– Monitor the situation — if water starts dripping from a ceiling or wall as the pipe thaws, shut off the main immediately
– Check the crawl space or other accessible areas for signs of pipe damage

If temperatures won’t rise: If a cold snap is sustained and temperatures remain below freezing for multiple days, active thawing or professional help is needed — don’t wait indefinitely.

How Long Does It Take to Thaw Frozen Pipes?

Hair dryer or heating pad on an accessible pipe: 15–60 minutes depending on the length of frozen section and temperature.

Electric heat tape on a pipe: 30–90 minutes.

Raising house temperature + open cabinets (passive approach): 1–4 hours for pipes in interior locations; longer for pipes in crawl spaces or exterior walls.

Professional thawing equipment: 30–60 minutes for most situations — professionals use specialized equipment that thaws pipes more quickly than consumer methods.

If the pipe doesn’t thaw within 1–2 hours of active thawing attempts: The frozen section may be longer or in a less accessible location. Call a plumber — sustained unsuccessful thawing attempts with a hair dryer on a pipe that isn’t responding usually indicates the frozen section is further back or in the wall.

FAQ

Q: How do I thaw frozen pipes without a plumber?
A: Apply heat to the frozen section with a hair dryer, heating pad, or hot towels. Keep the affected faucet open so water and steam can escape. Start from the faucet end and work back. Raise the house temperature and open cabinet doors under affected sinks. Never use open flame on pipes.

Q: Frozen pipes with no water — what do I do?
A: Identify which fixtures are affected, trace back to find the frozen section, apply heat. If you can’t locate or access the frozen section, keep the house warm and call a plumber. Shut off the main water supply if you suspect a pipe has burst.

Q: Will frozen pipes burst if I turn the heat on?
A: Warming the house (turning up the thermostat) is safe and appropriate. Pipes burst from ice expansion during the freeze — not from gentle thawing. The danger is using intense concentrated heat (torch, boiling water) that creates steam pressure; gentle warming from the thermostat doesn’t cause this.

Q: At what temperature do pipes freeze?
A: Water freezes at 32°F, but pipes in protected locations (interior walls, insulated spaces) typically don’t freeze until ambient temperatures drop to 15–20°F. Pipes in uninsulated crawl spaces, exterior walls, or garages freeze faster and at higher temperatures.

Q: Can frozen pipes thaw on their own?
A: Yes, if temperatures rise above freezing. Leave a faucet partially open on the affected branch so water can escape when thawing begins, and monitor for leaks. If a hard freeze continues and temperatures don’t rise, active thawing or professional help is needed.