How To Clear a Main Sewer Line Clog? (6 Step Guide)

Last Updated On April 11, 2024

Updated on August 30, 2022



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how to clear a main sewer line clog

A main sewer line clog occurs deep in your plumbing system and can cause a sewer backup in numerous other areas of your home. It can also make things smell quite unpleasant.

That’s why you need to learn how to recognize and clear a main sewer line clog. 

In this PlumbingNav guide, we will cover:

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

What's In This Guide?

      What You Need to Know About a Main Sewer Line Clog

      Your plumbing system starts with water entering your home at very high pressure from the main water supply. Most people get water from the city, but about 13 million households receive water from a private well

      The water travels through the water heater to the appropriate plumbing fixture in your home, including your toilet, shower, bathroom sink, and kitchen sink. 

      After you finish using it, the remaining water will flow out the drain and to the bottom of your home through the main line using gravity. The main line connects to the drain line that removes waste water from your home. 

      The main “drain” becomes your main sewer line on the exterior of your home. This will lead waste water to either your septic system (on private land), or to the city’s water treatment plant if you use their system. (About 20% of homes use a septic tank system that provides basic water treatment on-site).

      As you send certain items down your main drain from various sink faucets, toilets, shower drains, they can accumulate inside of your main sewer pipe and create a clog. 

      Some of the items that create a clog include:

      When you get a clog in your main line, you will know it soon enough. Multiple drains in your home may start to drain slowly. You may also have a foul odor emitting from your sink or shower drains. Left unresolved, you may even experience sewage backup entering your home. 
      Keep in mind that a toilet clog is different than a sewer clog. Read our article for help on how to unclog a toilet clog.

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

      Not all main sewer line clogs can be resolved by the homeowner if they are deep in the system, or beyond the reach of your basic tools. Using a sewer camera locator is very helpful in this situation. 

      It will not only help you identify the clog location, but if tree roots or a broken section is behind the cause, you’ll know that professional help will be required. Let’s cover how to clear a main sewer clog if it’s a routine situation. 

      Basic Tools 

      You may need some basic tools to get the job done. 

      Some of the tools you’ll need include:

      • Wrench 
      • Pliers
      • Screwdriver 
      • Hammer

      Snake Drain/Auger 

      A drain snake, also called an auger, fits into your drain to break up a clog at the source. Most augers only reach a distance of 25 feet. 

      You can use the auger to unclog a sewer drain in the basement floor or at the sewer cleanout cover if snaking from outside in the yard.

      Power Washer

      A power washer with a drain jetter attachment will send a powerful burst of water into your drain to break up the clog. Be careful.

      Ensure you are not filling up an already clogged drain with tons of water that has nowhere to go. This can create a sewer backup, and it might not be covered by your insurance.

      Chemical Drain Cleaner 

      You can use a chemical drain cleaner specifically made for your sewer line. The harsh chemicals in drain cleaners will bypass standing water to eat at the clog. 

      Some of the most common chemicals used in chemical drain cleaners are sodium hydroxide and sulfuric acid.

      How To Clear A Main Sewer Line Clog (6 Steps)

      After you troubleshoot your sewer line problem to ensure you have a clog, you need to take action. Follow these tips on how to clear a main sewer line clog.

      Step 1: Remove Drain Pipe Cap 

      To access your sewer line, you need to find a cleanout drain pipe cap. You can find them in the yard, flower garden, or in the basement of your home. 

      You may need a wrench to open the drain pipe cap. 

      Note: We highly recommend you first inspect your sewer line. This will help you identify the location and type of clog. You can do this with a relatively inexpensive sewer camera with locator. Avoiding damage is worth the small investment.

      Step 2: Feed Auger Into Pipe

      With the drain cap open, enter the auger into the cleanout. Continue to feed the auger into the pipe until you run into the clog.  If you don’t own one, check out our reviews on the best electric drain snakes. They aren’t very expensive.

      Step 3: Power Auger

      Once you reach the drain clog, power the auger to rotate the end of the device to break up the clog. If you have the option, you can change direction from clockwise to counterclockwise.

      Step 4: Use Chemical Drain Cleaner 

      If the auger can’t reach the clog, you may need to use a chemical drain cleaner. You need to use a chemical drain cleaner exactly as directed, especially when it comes to how long you leave the cleaner in your pipes.

      In most cases, you cant leave it in for more than 30 – 60 minutes. However, the best main line drain cleaners are specially formulated to leave in overnight.

      Look for products that claim to be safe for PVC plumbing pipes, cast iron, or whatever you have in your home. 

      If you suspect roots to be your issue, try using a root killer that dissolves tree roots in the sewer lines.

      Step 5: Power Washer

      Caution: This should be used with care as you can promote water backup if you don’t know what you’re doing.

      You can apply a sewer jetter onto your power washer to reach even further than you can with an auger. Once you reach about a foot deep into the blocked drain, you can turn on the power washer to apply pressure and hopefully break up the clog. 

      Again, if your system is clogged you need to be careful not to add even more water to the problem, which can promote a backup

      Step 6: Call a Plumber

      In many situations, you may need to call for professional sewer line cleaning. Of course, this comes with a bill. On average, the cost to clear a sewer line comes to an average of $475. However, the bill will vary on the exact services required. 

      Once you get a professional, check with your city to learn whether the cost is your responsibility or theirs due to its location. Depending on where the sewer clog exists, they may help cover the expense of the sewer lateral problem located on their side of the property line. 

      If your main line pipe has deteriorated, is broken, or has excessive corrosion, it may require replacement instead of repair. In this applies to your situation, learn about trenchless sewer line repair as a new and cost-saving method for fixing the problem.

      Step 7: Prevention

      Once you get rid of the clog, you need to take action to prevent another clog from developing. 

      One of the main ways to prevent a grease clog in your sewer pipe is to not dispose of cooking oil in your kitchen sink drain. Instead, you should collect grease and fat and dispose of it in the garbage instead of the drain. 

      You should also be careful about what food waste you put down the drain or garbage disposal. You especially don’t want to put coffee grounds, fibrous vegetables, and eggshells down the drain. 

      You can also use enzymatic drain cleaners as part of your regular plumbing maintenance once a month to keep the drains clean. 

      Final Thoughts on How to Clear a Main Sewer Line

      A drain problem in your sewer system can lead to expensive damage if it backs up into your home, causing water damage that may or may not be covered under insurance.

      In the case of an especially severe clog, you may need to call for professional sewer line cleaning if it is beyond reach, or if debris such as tree roots are behind the clog. 

      FAQs For How To Clear A Main Sewer Line Clog

      Can I unclog my own sewer line?

      Yes. You can unclog your own sewer line with an auger or caustic cleaner if it’s routine and within reach. In other cases, professional help is recommended. 

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

      To unclog a sewer line without a snake, you can try a chemical cleaner if hair and organic material are causing the clog. We recommend using a camera inspection device to identify the cause of the clog. 

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

      It will cost about $475 on average to have a professional unclog a sewer line.

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

      If you have a clogged sewer line, you should use an auger or a chemical drain cleaner. If the clog is serious, call a drain cleaning professional.

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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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