How do you thaw a frozen main sewer line?

Author: Jena Beatty  |  Last update: Sunday, November 30, 2025

Space heaters, hair dryers and heating pads are highly efficient tools for unfreezing a drain pipe. If a frozen drain line ruptures, turn off your home's main water supply. Patch the pipe, call a plumber and a water damage restoration company.

How to unfreeze a frozen sewer line?

To thaw the drain, fill a pitcher with hot water and pour it by way of a funnel into the center pipe. The hot water will begin to melt the ice, and the tube will inch its way down the drain. As you continue to pour the hot water down the center pipe, the cooled water will be forced upward into the outer pipe.

How long does it take for underground pipes to unfreeze?

In many cases though, using the right heating tools can unfreeze your pipes in a matter of 30-45 minutes. Doing this safely and without causing the pipe to burst is the real challenge.

Can you pour hot water down the drain to unfreeze pipes?

Pipe-thawing options: There are several things you can do to thaw your home's pipes. Here's a list: Probably the most popular and safest pipe-thawing option is to use hot water.

What happens if sewer line freezes?

Frozen sewer pipes can lead to a lack of water coming from your tap and to backups in the other pipes in your home. In the worst-case scenario, your frozen pipe can burst, causing a huge flood of sewage water all over your property. A burst pipe is much more expensive to repair than a frozen pipe.

3 Easy Steps to Thaw Frozen Sewer Pipes

Will pipes unfreeze on their own?

Your pipes will eventually begin to thaw on their own once the temperatures rise above freezing.

How do you know if your sewer vent is frozen?

From the ground, or if you can see the cap from a window, visually inspect to see if you can spot ice build-up. Don't go on your roof. If your toilet is slow or gurgles, this can also be a sign that the vent is plugged.

Can I flush my toilet if my pipes are frozen?

In most cases, no. Attempting to do so can cause pressure buildup in the pipe and lead to bursting. Additionally, flushing a toilet with a frozen pipe can result in unsanitary conditions due to a lack of proper drainage. Turn off the water supply and address the frozen pipe before attempting to use your toilet again.

Will salt thaw a frozen drain?

Tip #9: Hot Water and Salt Can Thaw Drainpipes

While we didn't have any issue with our drainpipes, our plumber also gave us this bit of advice: If your drainpipes freeze, boil a kettle of hot water. Stir a cup of kosher salt into the hot water, then pour the concoction down the frozen drain.

Should I turn off water if pipes are frozen?

Thaw Frozen Pipes

Turn off the water immediately at the main shut off valve. Open the faucet so that water will flow through the pipe once the area is melted. This will help melt more ice.

How do I unfreeze my hidden pipes in my house?

Apply heat to the pipe.

You can also use a small heater or heat lamp. If there is no electrical outlet, boil some water and soak a few towels in it. Wrap the pipe with these towels. When the towels cool, repeat the process until the pipe is completely thawed.

What do I do if my pipes are still frozen after 2 days?

If your pipes have been frozen for more than two days, shut down your home's water supply. Locate the frozen length using touch, sight and sound. Make sure the pipe hasn't burst, and open indoor faucets. Unfreeze the pipe using a hair dryer, heat tape, space heater or heating pad.

How much does it cost to unfreeze a pipe?

Burst pipes will need to be replaced and a plumber is best equipped to handle the job. The average hourly plumber rate is around $330, depending on where you live and the size of your job. As long as your frozen pipes haven't burst, a plumber will likely charge a flat fee of around $100 to thaw them out.

How do I unfreeze my main water line to my house?

There are several methods you can try, including a hair dryer, heat tape, or a space heater. You can also attempt to thaw out the pipe by simply turning up the heat in the home, but this will take much longer than one of the previously mentioned methods.

How do you tell if drain pipe is frozen or clogged?

  1. 5 Signs You Might Have a Frozen Drain Pipe. thogan. ...
  2. 1 Visible frost on a pipe. ...
  3. 2 Strange sounds coming from the pipes. ...
  4. 3 Unpleasant smells from the pipes. ...
  5. 4 Weak water pressure or no running water at all. ...
  6. 5 Keep an eye out for leaks.

How do you defrost a drain line?

Remove Any Visible Blockages: Use a turkey baster or pipe cleaner to clear out any debris or ice that might be clogging the drain tube. Flush with Warm Water: Fill a turkey baster with warm water and gently flush the drain tube to dislodge any remaining debris. You won't need any drain cleaners or harsh chemicals.

How do you thaw a frozen underground sewer line?

Most frozen icy waste removal jobs can be completed using the cold water supply from a garden hose. Heated water is usually not required. Use a sewer jetter with a nozzle that has a forward jet to help penetrate the icy clog.

Will dumping hot water down the drain unfreeze pipes?

Burst pipes are not only an inconvenience—they can result in devastating water damage and costly repairs. You may be wondering if pouring hot water down the drain will unfreeze pipes. The answer is “yes” if the frozen pipe is a drain pipe.

What can you pour down drain to unfreeze pipes?

Here are some tips that can help:
  • Boil water. Boil a generous amount of water and add a cup full of salt to it. ...
  • Baking soda. While the water is boiling, put around ½ a cup of baking powder in the drain. ...
  • Vinegar. Pour one cup of vinegar down the pipe immediately after putting baking soda. ...
  • Pour boiling water. ...
  • Run hot water.

Do pipes unfreeze themselves?

If your pipes freeze, you may consider just waiting for your pipes to thaw and unfreeze themselves. While pipes can naturally thaw over time, there are a lot of issues that arise from this risky method. Depending on the weather and climate in your area, pipes can take a long time to unfreeze themselves.

Will a toilet crack if it freezes?

“Frozen water can cause the toilet to crack, while freezing in the pipes connected to the toilet can lead to blocked water flow and, in severe cases, even cause the pipe to burst due to the expansion of ice,” says Fleming.

What is the best way to unfreeze plumbing?

How to unfreeze pipes
  1. Turn on the faucet. Keep it running. ...
  2. Apply heat to the frozen area. Slowly apply heat using a hair dryer. ...
  3. Continue to apply heat. Don't stop heating until the full water pressure is restored. ...
  4. Check all faucets and prevent pipes from freezing in the future.

How to keep sewer pipe from freezing?

How Can I Prevent My Sewer Line From Freezing?
  1. Insulate Your Pipes. When your sewer pipes are not properly insulated there is an increased risk of the water inside freezing. ...
  2. Seal Off Outside Vents. ...
  3. Inspect Your Water Heater. ...
  4. Run Water. ...
  5. Keep Drains Clear.

Where is my sewer vent pipe?

If you have a two-story home, go upstairs to locate the pipe. You can verify whether a pipe is a vent pipe by listening as someone flushes the toilet. If the pipe amplifies the flushing sound, it's likely the vent pipe. To find the plumbing vent on the roof, look for a pipe extending about six inches from the roof.

Does a sewer skewer work?

I finally ordered your skewer in December and it works perfectly, the final test coming this past week when it was -40 three nights in a row and no freeze up. My wife is happy I'll never have to climb up on the roof again with my thermos at 30 below."

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