Home Repair & Maintenance Ideas and Tips

What to Do About a Clogged Sewer Line?

Plumbing issues caused by clogged sewer drains can be expensive and frustrating for homeowners. AHS explains the signs of an issue and when to call in a pro.

clogged sewer lines

Is My Main Sewer Drain Clogged?

Strange gurgling noises coming from your toilet. Water bubbling out of your shower when you run the washing machine. Perhaps you are wondering what it means if sewage is coming out of the shower drain? These are some of the signs that you may have a clogged main sewer drain line — a serious plumbing issue.

A clogged sewer drain line can impact the plumbing throughout your entire home. In severe cases, you may wind up with raw sewage backing up out of your drains. And no one wants that.

What Causes a Clogged Sewer Drain Line?

In most cases, particularly in older houses, tree roots can interfere with the smooth operating of your sewage system. Attracted to the warmth and moisture of a sewer line, tree roots creep in through tiny cracks or loose joints in the pipe. Feeding on the plentiful nutrients they find there, the roots grow and create a blockage in the sewer line. Eventually, toilet paper or other debris gets snagged on the roots, further preventing water from flowing through the main sewer drain line.

Flushing sanitary products, such as paper towels, facial tissues, feminine hygiene products or even extra-thick toilet paper, can also clog your sewer line. However, this is far less often a problem. Assuming these items make it far enough, sewer pipes are typically 6 inches in diameter. In other words, it takes a lot of loose material to clog them.

Signs of a Clogged Sewer Line

Watch out for these early warning signs of a blocked or clogged sewer line, so you can address the problem before it becomes an expensive emergency.

  • Your drains are all running slowly, despite your best efforts to clear them. If you've tried all of the DIY unclogging tips on this list and you still can't seem to find a fix, it's likely the blockage is in your sewer line.
  • Several plumbing fixtures are clogged at the same time. If your toilets, kitchen sink and tub or shower are all backed up, you probably have a clogged sewer line. Toilets have the most direct route to the sewer, as well as the biggest drain line. If the clog is in your sewer line, you're likely to experience trouble with your toilets first. If your toilets are working fine while other fixtures in your home are still slow to drain or are backed up entirely, you probably don’t have a stoppage in your main sewer line.
  • When you flush the toilet, water backs up into or comes up in the tub or shower. When your sewer line is clogged, the water can’t go down the drain. Instead, it flows back up the pipes and comes out at the lowest point — usually the shower drain.
  • When you run water in the bathroom sink, the toilet bubbles and gurgles. The bubbling is due to air trapped in the plumbing system. Run the water in the sink closest to the toilet for about a minute. If the toilet bubbles (gurgles) or the water level in the toilet rises, you may have a clogged sewer line.
  • When your washing machine drains, the toilet overflows or water backs up in the tub or shower. If the toilets are still flushing fine, you probably don’t have a blocked sewer line.

How to Unclog a Sewer Line

Luckily, you can take immediate action to restore your plumbing system to a state of good health.

  • Release the pressure. When you first notice the symptoms of a clogged sewer line, turn off the water at the main supply (or street level). Survey your yard, basement or roof and see if you can find your sewer cleanout line. This is usually a short, white pipe about 3 to 4 inches in diameter and sealed with a screw-on cap. Once you've identified the cleanout line, remove the cap. This should release the pressure in the sewer line and force any water that has backed up into your home to drain.
  • Chemical drain cleaning. If tree roots are the culprit behind your sewer line clog, you can use chemicals to remove them. Some plumbers recommend flushing copper sulfate down the toilet to kill tree roots, but this substance flushes away quickly, meaning you may have to repeat the application several times in order to clear the clog. Be aware that copper sulfate is not safe for septic systems and its use is prohibited in some municipalities. If copper sulfate isn't a viable option for unclogging your sewer line, try flushing a root-killing foam containing the herbicide dichlobenil down your toilet. The foam sticks to the pipes and kills the tree roots within a few hours. However, it still may take a few months for dead roots to be completely flushed from your sewage system.
  • Mechanical drain cleaning. Sewer cleaning professionals have a few tools at their disposal for unclogging main sewer drain lines. Among the most effective is a specially designed, flexible cable that's popularly known as an auger or drain snake. The auger is often power-assisted — some are even truck-mounted — and can be fed into the sewer line in sections until the plumber is able to reach and break apart the clog. Plumbers may also use a high-pressure water jet to blow the roots and other debris down the sewer line. While you can rent these tools and do it yourself, both can damage your pipes if used incorrectly. Cleaning a clogged sewer line is a job best left to the professionals.
  • Camera inspection. If the auger or water jet doesn’t unclog the sewer line, you can request a visual (camera) inspection to determine what's causing the blockage. The miniature camera can reveal cracks and breaks in the sewer pipe, as well as problems in the line that may require your local sanitation department's attention.

One of the best ways to protect both your home and your peace of mind is with a home warranty from American Home Shield. Our Systems Plan provides coverage for your home's plumbing fixtures and pipes. If you’re already an AHS member, we’re here for you when you need us. You can request service in MyAccount 24/7.

DIY tips are for informational purposes only. Learn more.

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