How to Thaw Frozen Sewer Line – Step by Step Guide

In the winter months, if temperatures tend to drop below freezing in your area, it is possible that one day you will run into a situation with a frozen sewer line. It makes sense – water expands when it is exposed to freezing temperatures.

Fortunately, this is not a common occurrence, but it is certainly an inconvenient one that can cause damage like a burst pipe if left for too long. Before you call the plumber, you may wonder can you learn how to thaw frozen sewer line yourself?

Yes, you can! There are a few things you can try before you call the plumber, just by using some common household tools and a little bit of know-how.

septic system sewer lines

There are two effective methods you can potentially use if you want to know how to thaw frozen sewer line. You can either apply heat directly to the frozen part of your line using a heat lamp, space heater, or heat tape, or you can spray water into the line using a garden hose. In either case, though, the first step is the same: locate the frozen blockage in the sewer line.

Let’s learn more!

How Do You Find Where My Pipes Are Frozen?

This could be in a basement, crawl space, outdoor sewer access pit, or any other cold area related to your home. If you find that it is in the drainpipe, immediately refrain from your normal use of the water. If your wastewater cannot flow freely, you may also need to find a way of containing it, like in a large bucket.

The first thing you should do is look carefully at any easily accessible pipes for bulges, ice, or frost. If you do not notice anything visually, you can feel the pipes with your hands to see if you can notice any spots where they feel especially cold.

If you have water supply issues, you can also narrow down which pipe is frozen by turning on faucets and seeing which ones do not work properly. Once you have determined the frozen pipe, you can trace it down to where they split off with your other pipes and go from there.

How to Thaw Frozen Sewer Line

Method 1: Direct Heat

direct heat

Step 1: Gather supplies

  • Space heater, heat tape, or heat lamp
  • Blankets

Step 2: Place the space heater or heat lamp next to the suspected blockage in the sewer line

Use blankets to both direct the hot air and protect the pipe from the cold air. While this is a simple method, it may take hours for the space heater and blankets to help fully thaw the line.

OR Use heat tape

Wrap the tape around the frozen area. Locate a 110-volt outlet and connect the other end of the heat tape.

While these methods are effective in that they gradually defrost your pipes, they make take hours. After you are certain that everything has melted, remove the heat source from the pipe.

Step 3: Wait

Method 2: Garden Hose

garden hose

Step 1: Gather supplies

  • Garden hose
  • Funnel
  • Hot water
  • Bucket

Step 2: Insert a garden hose into the sewer line

For it to fit smoothly, the hose must be smaller than the diameter of the drain line. Keep inserting until you cannot anymore – this means you have reached the blockage.

Step 3: Pour hot water into the hose

Hold your end of the hose up and use the funnel to carefully pour hot water into it from a spouted container like a kettle. The hot water should start melting the frozen blockage. Have your bucket on hand to catch any overflow, as the hot water will flow back during this process.

Step 4: Once the blockage has cleared, pull the hose out and clean it

Sterilize your hose with something like disinfectant wipes. Finally, clean it off with a clean, wet rag or paper towels.

Can I Just Wait for Frozen Pipes to Thaw?

Technically, you can just wait for your frozen pipes to thaw, but there are risks. When the ice in the pipe starts to melt, it can create more pressure within the pipe as the water gets trapped between the faucet and ice. This increased pressure can cause a burst pipe, so if you prefer to wait for your pipe to thaw, proceed with caution.

Will Pouring Hot Water Down the Drain Unfreeze Pipes?

You can potentially unfreeze pipes by pouring hot water down the drain, but there are also risks involved with this method. The first issue is that you could damage your PVC pipes, as they can expand quickly when exposed to hot water. This could lead to cracked pipes. The second problem is that the pipes could burst when exposed to hot water due to pressure build-up. If you choose to try this method, again proceed with caution.

How Do You Know If Your Sewer Line Is Frozen?

Many signs can be indicative of a frozen sewer line:

  • Icy or bulging pipes
  • Noisy sewer system
  • Flooding
  • Moist ceilings and walls
  • Smelly drainage system
  • No running water

How Long Does It Take for Pipes to Unfreeze?

This depends on what method you are using to unfreeze your pipes. If you want them to unfreeze on their own, it depends on how cold the weather in your area continues to be, but the process could take days. If you use one of the heating methods above, it could take hours. If you use the garden hose method, it could potentially only take 30 minutes.

Can You Flush the Toilet If Your Pipes Are Frozen?

Yes and no. If your water supply pipes are frozen, then you can potentially flush your toilet as you normally would once as there should be enough water in there from before you started having problems.

After that, if there is no running water getting to your toilet, you will not be able to flush normally, but you can still flush. You just need to add the water manually, either to the tank or to the bowl.

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