The 6 Signs of a Frozen Pipe, and How to Fix Them

Every cold season sees the danger of frozen water pipes. While we take hot water and indoor plumbing for granted, all it takes is one burst pipe to disrupt the household and lead to additional repairs from water damage.

The average cost of a burst pipe repairs ranges from $100-$200 per foot, but most households end up forking between $400 to $1,500, depending on the length of the affected waterlines. And this doesn’t yet include the clean up and repair bill for the water damage, which can pile on an additional grand or two.

To avoid this nightmare, it helps to know how to spot a frozen pipe. Here are five danger signs to watch out for, and what to do in case it happens.

Warning Sign #1: -20 Degrees

The freezing point of water is 32 degrees Fahrenheit. Thankfully, indoor pipes are insulated from outside temperatures, so they can function below freezing weather.

It’s when the external temperature falls below -20 degrees F that pipes are in danger of freezing. So keep an eye out for the local temp each day.


Warning Sign #2: 6 Hours Below Freezing

If outside temperatures fall below -20 degrees F for six consecutive hours or more, there’s a good chance that your pipes may have frozen. 

Hence, be careful of overnight freezing temperatures. Most cases of burst pipe damage happen in the morning, when homeowners first wake up and turn on the tap without checking.


Warning Sign #3: Frost Formation

This one should be obvious, and yet a lot of people miss it. The clearest sign of a frozen waterline is when frost forms on the pipe exterior. So before reaching for the faucet, take a quick look below the sink, and tap the metal for signs of ice formation.


Warning Sign #4: No Running Water

If only a trickle comes out of the faucet, or no water at all, that’s a giant red flag. Immediately close the tap before water pressure builds up and bursts through the affected area.


Warning Sign #5: Odd Smells

If you notice a strange odor emanating from a tap or sink, it might be a sign of a frozen or blocked pipe. This is because a blocked pipe obstructs the odor from circulating inside the line, so it has nowhere to go but back out the faucet.

The odor can vary depending on your geographic location, water quality, and the condition of your water line. But common bad odors include:

  • Metallic smell
  • Sulfurous stink
  • Earthy smell, like just after it rains
  • Sewage odor


Warning Sign #6: Water Hammer

If you hear a loud series of bangs when opening the tap, chances are you’re hearing the sound of a water hammer. This is when the high water pressure gets blocked, so it slams into and builds up inside the pipe. As a result, the pipes themselves may jerk around and clatter against other pipelines or within the wall framing. 

A water hammer is a catastrophic sign and the water supply should be turned off immediately, before the pipes burst from the pressure.


What to Do in Case of a Frozen Pipe Situation

Turn off the tap

Immediately close the faucet and warn all family members. If possible, shut off the water supply to the suspect area to stop the flow of moving water.


Inspect the pipeline

Check the pipes in the affected sink for these signs:

  • Frost formation
  • Dripping water
  • Pooled water under the pipe
  • Misalignments

If the pipes have been knocked out of alignment or ruptured, keep the water supply closed and call a plumber. Otherwise, you can thaw the pipe.


Keep the door open

For under sink pipes, keep the cabinet door open. This will allow the warm air circulating in the house to get through to the pipe and mitigate freezing.

If it’s in the bathroom, keep the door open so the warm air will rush in and fill the space.


Open the faucet

Once you’ve determined there are no ruptures, open the tap. The thawing process will generate water and steam, and these will need to be discharged out of the open faucet.


Apply heat

There are several ways you can thaw a frozen section of piping:

  • If there’s a nearby outlet, you can use an electric heating pad. Just make sure the outlet has a ground-fault circuit interrupter (GCFI) for safety.
  • If the pipe is accessible, use a hair dryer.
  • If you lack either of these, you can also use towels soaked in hot water and wrapped around the pipe.
  • If you wish to use a space heater, make sure the space is clear of flammable materials, and never leave it unattended while turned on.

NEVER use these items to try and thaw the pipe:

X Kerosene or propane heaters

X Open flame devices such as charcoal stoves

X Blowtorches


When in doubt, call a professional

Thanks to metal conductivity, a frozen pipe is rarely a single occurrence. If you spot one, chances are there could be others. 

If you can’t check the rest of the pipes, or if they lie in an exterior wall, call the plumber rather than risk greater damage.


To stop pipes from freezing in the first place, check out our guide to Burst Pipe Prevention.


Mickey Luongo

Mickey is the resident heating and air conditioning expert with over 15 years of experience in the industry.

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