How To Unclog a Sewer Drain in the Basement? (4 Step Guide)

Last Updated On June 11, 2024

Updated on April 28, 2022



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how to unclog a sewer drain in the basement

The sewer drain is the unsung hero in any home, transferring the waste exiting your drains away from your home to the appropriate destination. 

A clogged sewer drain can mean disaster if not detected and treated with a sense of urgency. However, by the time you realize you have a problem, you probably have a stubborn clog on your hands. 

In this PlumbingNav guide, we will cover:

  • What you need to know about how to clear a main sewer line
  • Supplies you’ll need to clear a main sewer line
  • How to clear a main sewer drain line

What's In This Guide?

      What You Need To Know About How To Clear A Main Sewer Line Clog

      We’ve advanced immensely since the beginning stages of residential plumbing, but clogs and leaks in the sewage system are bound to happen.

      To start, it’s a good idea to understand how your home plumbing system works when it comes to the drain system.

      All the unused water in your home makes its way through each drain, whether this is the sink, shower, or toilet drain. Every smaller drain leads to what is called the main drain line, which is a larger diameter pipe.

      This is located in your slab foundation 90% of the time if you live in the South. If you live in the North, it will be located in your basement.

      This main drain line moves waste water out of your home. Once the drain pipe exits your home, it’s typically called the sewer lateral. This is either connected to a septic system if you’re on private land, or the city sewer system. (80% of homes in the U.S. are on a city water system.)

      It continues along this journey until all waste finally reaches the local treatment plant. Of course, the setup varies slightly from municipality to municipality. 

      People may refer to the main drain and their sewer line as the same thing. For the purposes of this article, we will combine these terms as we help you learn how to unclog it. 

      How long do sewer line drains last? 

      Sewer lines often last 50 to 100 years. Many older sewer pipe materials were made of cast iron, and these can and will corrode over time. Cast iron sewer pipes’ life expectancy is about the same, however, if caustic chemicals are used this can speed corrosion.

      What causes sewer line clogs?

      As items flow down your drain, they can accumulate in the sewer pipe. 

      The main culprits include grease and fat, which makes it especially important for every homeowner to do their part to avoid creating a grease clog by not pouring hot oil, grease and fat down the drain.

      Tree roots may also create a blockage in the portion where your sewer drain is buried in your yard.

      Other things that can create sewage backup include:

      • Paper products (“flushable wipes”)
      • Hair 
      • Food waste
      • Foreign objects

      How do I know if I have a sewer line drain clog?

      Early detection can save you a lot of money and hassle, so it’s important to know what to look for.

      A sewer line clog will typically first be noticed by slow drains, toilets that don’t fully flush, water backing up. What’s different here is the problem will affect multiple drains and toilets, not just one.

      It can also result in leaks in your yard or begin to backup in your house if the pressure becomes too much. It can also cause a broken plumbing fixture. 

      Here are some of the signs of sewer system failure:

      • Gurgling toilet and other plumbing noises
      • Foul odor
      • Sewage backup
      • A clogged drain in sinks and showers
      • Discolored water
      • Basement flooding

      Sewer backup, in particular, can be a mess to deal with, and a flooded basement comes with expensive repairs. By the way, plumbing is not always covered by homeowner’s insurance.

      did you know how to unclog a sewer drain in the basement

      Supplies You’ll Need To Clear A Main Sewer Line Clog

      We are going to begin with the simplest and cheapest remedies for how to unclog a sewer drain in your basement.

      Drain Cleaner 

      A drain cleaner can eat through the material creating a clog if it’s basic.

      You have three main options when it comes to drain cleaners:

      Not all options are the same. You want to choose the best drain cleaner for the main line, as it will be specially formulated for the job. Follow the instructions, and use it up to 3 times. If this step didn’t unclog your basement’s sewer drain you will need more horsepower.


      An auger reaches deep into your plumbing system to break the clog up at the source with a pointed end, making it an immediate and effective solution. You can use hand crank models or power drain augers.

      The physical action on the auger will disrupt most sewer drain clogs, that is if they can reach them. Most augers reach 25 feet, and can reach the main line clog. There are 50′ options as well, so calculate how much reach you will need.

      Protective Gear

      Working on a sewer drain can get messy. That’s why it’s important to have adequate protective gear. 

      Look for old clothes that cover your arms and legs as well as gloves and goggles. Sewage water contains bacteria and other materials that can be harmful. You want to ensure that you don’t come into direct contact with it. 

      How To Clear A Main Sewer Line Clog (4 Steps)

       In most cases, the best way to access your main sewer line is through a basement floor drain or cleanout. 

      Step 1: Turn Off Water

      Start by turning off the water to your home. In most cases, you’ll find the water main near the water meter. 

      Turning off the water prevents additional water damage in the case of any leaks or a complete clog. It also allows you to reach the clog instead of trying to work through standing water. 

      Step 2: Drain Cleaner

      Once you allow the water to clear out of the main drain, apply the drain cleaner of your choice. 

      A chemical drain cleaner may work on tough clogs quickly, but it can potentially damage your pipes. 

      On the other hand, an enzymatic drain cleaner may require you to wait overnight, and even the best natural drain cleaners aren’t as effective as chemical drain cleaners.

      That’s not to say that natural drain cleaners don’t work. However, they work better as part of plumbing maintenance as opposed to handling tough clogs. 

      Step 3: Drain Snake 

      If you have access to an auger, enter it into the nearest drain to the clog that is closed to the main line. This will reduce the need to turn corners.

      The sewer cleanout cover is typically located on your basement floor, or in a corner of the house sometimes in a closet. Remove any cover and place the auger into the drain, guide it until it reaches the sewer clog. 

      If you cannot find it anywhere, or you do not have a basement, you can try gaining access by removing a shower drain cover or also snake it from the outside.

      Once you have reached the clog, turn the power on to break up the clog. If you’re using a hand-powered plumbing snake, travelling back and forth directions to fully break it up.

      Step 4: Call A Plumber

      If the clog still doesn’t clear up, it’s time to enlist professional sewer line cleaning

      On average, having a plumber clear out your sewer line will cost $475. However, you should look up information in your area about whether the responsibility for the repair falls on you as the homeowner or the city.

      Final Thoughts On How To Unclog A Sewer Drain In The Basement 

      If you notice a clogged basement drain, you probably have a sewer clog that could lead to unpleasant drain backup. Take action before the problem gets out of control using our guide on how to unclog a sewer drain in the basement. 

      Once you create a drain opening, take the proper precautions to prevent the problem from happening again by not pouring grease down the drain and using natural drain cleaners monthly. 

      FAQS For How To Clear A Main Sewer Line Clog

      Can I unclog my own sewer line?

      Yes! You can unclog your sewer line yourself using a drain cleaner, an auger, or a power washer 

      How do you unclog a main sewer line without a snake?

      To unclog a main sewer line without a snake, you should try a drain cleaner or a power washer.  

      How much does it cost to unclog a main sewer line?

      On average, it costs $475 for professional sewer line repair. 

      What can I do if my main sewer line is clogged?

      If you have a clogged sewer line, follow these steps:

      • Step One: Turn off your water
      • Step Two: Use a drain cleaner
      • Step Three: Use a drain snake
      • Step Five: Call a plumber

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      About Plumbing Navigator

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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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