How to Thaw Frozen Pipes Underground (5 Steps)

Last Updated On June 11, 2024

Updated on March 22, 2022



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how to thaw frozen pipes underground

Do you have frozen water pipes underground? You may wake up on a cold day to discover that you have no water coming to your faucet when you turn it on, despite the power still being on.

This can obviously cause your household significant discomfort and stress while you wait to shower, cook, and clean like normal. In some cases, you may have to wait for the city to take action depending on where the problem lies. However, you may have the ability to take things into your own hands and thaw your frozen water pipe.

This article covers your water supply line that is an underground pipe leading to your home, and not a frozen drain pipe or other indoor pipes found inside your home.

In this PlumbingNav guide, we will cover:

  • How to thaw frozen pipes underground
  • The DIY way to thaw frozen water supply lines to the house
  • Supplies to unthaw a frozen section of a water line
  • How to unthaw frozen pipes underground: public water and private wells

What's In This Guide?

      How to Thaw Frozen Pipes Underground

      Your underground water supply pipes bring water to your home from your home’s water source, whether that be the city or a personal well.

      Freezing pipes can occur whenever temperatures fall below freezing, which happens everywhere in the country. Southern states (and Hawaii) that don’t experience freezing as much may find themselves even more vulnerable to frozen pipes when cold weather happens since many homes aren’t prepared for it, like homes in the North.

      How to Identify Frozen Supply Lines

      Thawing out your pipes quickly can prevent expensive damage. If temperatures reach freezing, keep your eyes open for warning signs.

      Signs of frozen supply lines include:

      • Freezing temperatures
      • Low or no water pressure to all fixtures
      • Frost on your faucets
      • Strange smells

      Dangers of Frozen Pipes

      When supply pipes get too cold the water inside will freeze. The ice prevents water from getting through to your house to the point you may not get any water at all.

      As we learned in science class, water expands when frozen. As the water turns to ice and fills your supply line, it can expand to the point a water pipe burst.

      Prevent Frozen Pipes

      We are going to deal with underground pipes in a second. However, you can also prevent frozen pipes inside before they happen with these simple tips:

      • Set temperature to 55°F or above inside your home, when leaving for the day or on vacation
      • Properly insulate your basement, if applicable
      • Protect or disconnect outdoor faucets
      • Insulate any exposed pipe

      This will help rule out frozen pipes on the inside of your house that restrict water. For hose spigots, consider installing a freeze proof outdoor faucet.

      We’ll now discuss how to thaw frozen water pipes outside and underground which supplies water to your home.

      did you know how to thaw frozen underground water pipes

      The DIY Way to Thaw Frozen Water Supply Lines To House

      In many cases, you may be able to thaw frozen pipes underground yourself. However, you should know that laws may restrict what you can do, and the job isn’t for beginner DIY plumbers.


      • Check the laws in your area to verify you have the right to work on the supply lines. You may need to enlist professional services or get a permit to do the work yourself if removing a water meter for access.
      • Find your water supply main shut-off valve and cut off the water at the source (consider installing a backup shut-off valve as incoming water can cause serious water damage).
      • Check with your insurance company to learn if you’re covered if things go wrong
      • Never apply an open flame to your pipes (ex. A blow torch)
      • Use caution with electrical devices around electricity

      Ok, now that the lawyers are happy let’s talk details.

      Supplies You’ll Need to UnThaw a Frozen Underground Water Line

      Water Pump

      An electric water pump will allow you to force water into your supply line. You will need an electrical source. A “pond pump” should give you the perfect amount of power for this particular task.

      PEX Pipe

      You will need a hose that isn’t frozen. We suggest PEX pipe or PVC pipe thanks to its flexibility and cost-effectiveness, but you can also use a nylon hose.

      You may need an adapter to connect the hose to the pump and the water main. Check connections to both devices and procure an adapter if necessary.

      Water Container

      You will need a container with high edges that holds at least 5 gallons to catch the ice as it melts.

      Alternative Options

      Some people try heat tape, an electric space heater, or a hairdryer to thaw pipes.

      While sometimes effective, they won’t reach deep into your plumbing system.

      Quick Reference Shopping List:

      Here are the products mentioned above, in a list format. Note, the size of the flexible pipe and fittings must be catered to the size you need at your home. This is an example setup, but be sure to check your own measurements. 

      Here are some supplies to point you in the right direction and make it easier:

      Shut off valve

      Water pump

      Adapter for pump to pex

      Pex flexible pipe

      Large water bin

      How To UnThaw Frozen Pipes Underground: Public Water & Private Wells

      At this point, you really need to see a video to understand the big picture. Here are 2 videos depending on your water source:

      City Water: How I thawed out a frozen underground water supply line from the street to my house

      Well Water: DIY – Quickly THAW your FROZEN Water Lines

      Here are the steps fully outlined so you can follow along…

      Step 1: Turn Off Water

      Turn off your water at your main water supply!

      If you don’t, you may experience a rush of water entering your house that can cause serious water damage.

      We suggest taking an extra cautionary step of adding a backup shut off valve to your system in case something goes wrong with the first one (the damage can be that devastating).

      Step 2: Access Your Main Line

      Once you turn the water off, access your main line.

      In a household that receives city water, you can access your main line by removing the water meter. *Make sure you’re allowed to do this based on city code.

      In most homes that use well water, you can access the main line from your basement or garage, although this will vary.

      Step 3: Feed Hose Into Main Line

      With an exposed pipe giving you access to your main line, you will feed a hose into the pipe.

      You will stop feeding the hose once you reach the ice blockage.

      Step 4: Attach to Pump and Place Pump in Bucket

      Once you reach the blockage, connect the hose to a small electric pump (that wont become damaged when it comes into contact with water).

      Put the pump in a 5-gallon bucket (or larger).

      Step 5: Activate Pump

      At this point, you can activate the pump. It will force water into the system, thawing the ice.

      It doesn’t matter if you use hot or cold water. The pressure causes the ice to melt, despite the temperature.

      Watch carefully that the bucket doesn’t fill up and overflow.

      This can take some time! One person indicated that it took 12 hours. Be patient.

      You know the job is done when no more water melts into the bucket.

      Special Considerations on Thawing Frozen Water Supply on City Water

      If you receive city water, you more adhere to their regulations.

      First, you should determine liability for the frozen pipe, which can vary from location to location. In many municipalities, the city takes responsibility if the pipe freezes past the curb, but you remain responsible for everything before that point. Check your township for exact details.

      You may not have the right to work on a frozen pipe yourself. Verify with the city about what you can and cannot do.

      Finally, check with your insurance company to learn what is covered. You may void your insurance claim if you work on the frozen pipe instead of letting the insurance company pay a plumber to do the job for you.

      Tips For Thawing Frozen Underground Water Pipes on Well Supply Lines

      When you receive your water from a well, you have more control over what you can do.

      You won’t need to ask the city’s permission to perform any work on a frozen pipe, but they also won’t take on any of the responsibility for the frozen pipes.

      Final Thoughts On How to Thaw Frozen Pipes Underground

      A frozen underground pipe can lead to a long wait for water at the faucet if sub-zero temperatures persist. You can often prevent pipes from turning to ice which results in a burst pipe on the inside of your home when freezing temperature arrives. However, the frozen ground outside may affect the supply lines before the water reaches you.

      We hope this guide was useful to help you get cold and hot water flow to your home sooner than just waiting for blockages to melt on their own.

      Keep in mind this process of opening and accessing your water lines will result in air entering the plumbing system. You will experience “sputtering” for up to a couple of hours. To expedite the removal of air trapped in your water lines, make your way to faucets and toilets and run them for a few minutes. This should clear the problem.

      Didn’t work? If your underground pipes were damaged in the freeze, you may need a camera locator. Should an underground supply or drain pipe need replacement that is out of reach, be sure to read up on trenchless pipe repair before agreeing to repairs. This can save you a lot of money, but not every plumber offers it. Find one who does.

      FAQs on Unthawing Frozen Underground Water Pipes

      How long does it take underground pipes to thaw?

      Thawing frozen pipes can take a significant amount of time (up to 12 hours). Practice patience and prepare not to have water for the majority of the day.

      What temperature do underground pipes thaw?

      Pipes thaw naturally once temperatures increase above freezing. The frozen ground area around the frozen underground pipe will contribute, too, causing natural thawing to take an especially long time.

      Can I just wait for frozen pipes to thaw?

      Possibly, but if your weather forecast calls for cold temperatures for an extended period of time you may not want to. Your family needs proper access to water immediately, and plumbing companies will often be backed up.

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      About Plumbing Navigator

      We write about "all things plumbing," helping you navigate common questions, repairs, and the best plumbing products on the market.

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      We write about “all things plumbing,” helping you navigate common questions, repairs, and the best plumbing products on the market.

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