How to Know if Your Pipes Are Frozen

View of a frozen pipelines and valves

Are your pipes frozen? While no water flow is an obvious sign of a problem, there are other signs you can look for to help you troubleshoot a problem. 

From checking to see how the outside of the pipe surface feels to whether or not there is an odd smell coming from the drains, learn how to know if your pipes are frozen so you can quickly troubleshoot and get water flowing again.

And how do you unfreeze pipes or thaw water in pipes? I’ve included my tip on how I unfroze my bathtub pipes with boiling water from the stove and a space heater in my bathroom.

No Water Flow

close up image of two frozen pipes
Photo Credit: Cha già José / Flickr / CC BY-SA 2.0

The most telltale sign of frozen pipes is a sudden lack of water or a significant reduction in water pressure when you turn on the tap. Unfortunately, if the water flow stops entirely during periods of frigid weather, it’s highly likely your pipes are frozen.

Unusually Cold Pipe Surface

If you can access a pipe, touching the outside of it with your hand is an excellent way to check if it is frozen. A section that feels much colder than other areas could indicate that it has frozen.

Frost on the Pipes

Visible frost on exposed pipes, especially in unheated areas like basements, attics, or garages, is a good indicator that your pipes are frozen. 

When the water inside a pipe freezes, the pipe’s surface becomes incredibly cold. As warmer, humid air around the pipe comes in contact with this cold surface, the moisture in the air condenses on the pipe, forming a layer of frost. 

Odd Smells Coming from Drains

If you notice strange smells — ones that smell like sewage — it may indicate your pipes are frozen and blocked. 

Ice in the plumbing traps any gases or odors in the pipes, preventing them from escaping through the drainage system. These odors can be from stagnant water, bacteria, or sewer gases that usually vent out.

Unusual Sounds Coming from Pipes

Frozen pipes can also make some funny noises. As the pressure changes within your pipes when they start freezing, and water and ice move through the plumbing, you might hear some unusual sounds. 

  • Pressure from ice expansion — water expands about 9 percent when it freezes — can cause pipes to shift or knock against other pipes or walls. This can cause a banging or clanging noise.
  • As water tries to move around the ice blockages forming in the pipes it may create a bubbling or gurgling sound. 
  • When pipes are partially frozen, and water is being forced through a narrow opening, you may hear a whistling noise from the restricted flow.
  • You may hear popping or cracking noises as the pipe material responds to the stress of the ice expansion within the plumbing.

If your pipes are frozen, you might also notice a lack of typical water flow sounds when a faucet is turned on. 

Bulging or Cracking Pipes

frost on two frozen pipes
Photo Credit: Vector Chernov / Adobe Stock Free / License

In severe cases, you may notice bulging in areas of the pipe, especially if you have plastic or PEX plumbing. The bulging is caused by ice expansion, and if not addressed quickly by thawing the frozen pipes, it could result in leaks or bursting.

FAQ About Frozen Pipes

At what temperature do pipes freeze?

Pipes can freeze anytime the temperature dips below 32 degrees Fahrenheit if they haven’t been adequately winterized or insulated for the season. However, once it drops further and gets below 20 degrees Fahrenheit, the chance of freezing increases considerably. Plus, the longer the thermometer is below that 20-degree mark, the higher the likelihood of frozen pipes.

How long does it take for pipes to freeze?

Many factors contribute to the time it takes pipes to freeze, including the temperature, the type of pipes, the pipe wall thickness, insulation, etc. Metal pipes freeze quicker than plastic, and thinner pipes freeze faster than thicker ones. Uninsulated pipes freeze sooner than insulated pipes.

White’s Plumbing & Electrical, LLC, says, “Pipes are most susceptible to freezing when the outside temperature is below 20 degrees Fahrenheit and there is little or no wind. Under these conditions, it can take as little as two hours for pipes to freeze. On average, unless under extreme conditions, it will typically take your pipes just six to eight hours to freeze if left unprotected. This means, if they are unprotected even just overnight, they run the risk of freezing.” 

How long can pipes stay frozen without bursting?

It’s hard to say how long pipes can stay frozen without bursting — there isn’t a definitive answer as so many factors play into the equation (e.g., type of pipes, temperature, exposure conditions, age of pipes, etc.). They don’t typically burst immediately when they freeze, but the risk increases the longer they stay frozen, and the pressure from the ice stresses the pipes. In many cases, it takes at least a day or two for frozen pipes to burst, crack, or split.

Are plastic or metal pipes more likely to burst?

Metal pipes are more prone to bursting than plastic due to pressure buildup from the ice expansion; plastic pipes have some flexibility and can accommodate some expansion. Regarding metal pipes, copper and brass pipes are less likely to burst than cast iron or galvanized steel.

What is the best way to unfreeze pipes?

The safest and most effective way to unfreeze pipes is to warm the frozen section and the surrounding area gradually. You can do this by running a space heater nearby, or if you can access the pipes directly, use a hair dryer, heat tape, or even hot, wet towels to heat the pipe itself.

My Tip: If you can’t access the pipes directly, you may have to get a little creative. When my bathtub pipes would freeze, I would boil water on my stove and put as much in the tub as possible. Since the pipes didn’t touch the tub directly, I didn’t worry the hot water would heat the pipes too quickly and crack them.

Between the hot water in the tub and running a space heater in my bathroom, it would create enough ambient heat to unthaw the pipes over time. It didn’t work as quickly as it could have if I had direct access to the frozen pipes, but it proved effective.

How can you keep your pipes from freezing?

To keep pipes from freezing, maintain a consistent indoor temperature by keeping the thermostat on, even if you’re away, and consider a smart thermostat to manage temperatures remotely. Let a faucet drip slowly in vulnerable areas, as moving water is less likely to freeze. Additionally, insulate pipes in unheated areas or use pipe heating cables to provide extra warmth during cold spells, which can protect them from freezing temperatures.

Spot the Signs Before It’s Too Late

One of the most frustrating things for homeowners is when their water stops working, and in the winter, frozen pipes are a typical culprit. If you think your pipes are frozen, you must know the common signs mentioned above so you can switch to fix-it mode and try to get them unfrozen before they burst and cause damage to your home. 

Awareness and swift action are your best tools for safeguarding your pipes!

Main Image Credit: Luka / Adobe Stock / License

Amanda Shiffler

Most comfortable with soil under her fingernails, Amanda has an enthusiasm for gardening, agriculture, and all things plant-related. With a master's degree in agriculture and more than a decade of experience gardening and tending to her lawn, she combines her plant knowledge and knack for writing to share what she knows and loves.