Find the common causes for a clogged or backed up sewer line in Portland, OR

Common Causes for Clogged Sewer Lines

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If you’re reading this post, chances are you’re experiencing some rather unpleasant signs that might indicate a problem with your sewer system – whether it’s a foul smell, backed-up drains or something similar. Oftentimes, problems that arise with drainage or sewage backups are caused by a clogged sewer line.

Your main sewer line is the piping system that transports all of the wastewater from your toilets, sinks and tubs away from your house to your city sewage connection. All of the drains inside your home exit to the city’s sewer system through this main line, so it’s easy to see how quickly problems can arise if it’s clogged.

It’s important to note that this post doesn’t apply to homes that use a septic system. If you’re worried that your septic tank is backed up, check out this blog to learn more about the potential culprits.

Here, we’ll cover the top four warning signs of a clogged main sewer line as well as ways to diagnose and fix the problem so you can return to a stress-free shower, toilet and sink experience.

Symptoms of a Clogged Sewer Line

The good news is that if your main sewer line is clogged, it shouldn’t take long for you to find out. There are a number of tell-tale signs that should be cause for concern, including:

  • Drains in your house are slow to empty or appear clogged.
  • There’s standing water in your yard or on your property near your sewer cleanout, which is the pipe that provides access to your main sewer line.
  • Water backs up in your shower when you flush your toilet.
  • You found sewage in a floor drain inside your home, whether it’s a drain in your shower, tub or basement.

If you experience any of these issues, the worst thing you can do is ignore them. Clogged sewer lines will only continue to cause backup and could turn a small problem into a much larger (and more expensive) headache over time.

The Culprit(s)

The first step in remedying the problem is diagnosing the root cause. There are several factors that could cause your main sewer line to become clogged. Common causes include:

  • Broken or misaligned pipes: Just like all good things, sewer pipes may eventually break. Broken pieces of the pipe may then block water and waste from freely flowing through.
  • Debris: Sewer lines may begin to sag over time, which could allow surrounding debris like dirt and rocks to enter the pipes, leading to a clog.
  • Grease/fat: Let’s face it – we’ve all put things down our drain that don’t belong there. Letting grease or fat trickle down your drain can be especially problematic, as these substances harden over time and can build up to completely block your sewage flow.
  • Tree roots: If your main sewer line is buried near a large tree or bush, it’s possible that its roots have broken through your pipe and blocked it. Plants are attracted to the closest sources of moisture.
  • Sagging pipes: Harsh climates like Portland’s may cause the soil around your pipes to shift, which could cause your pipes to bend or sag. Paper and waste may then collect in this “bellied” section of your pipe, leading to blockages.

Whatever the case may be, it’s important to correctly diagnose the problem to determine a solution. An easy way to do this is to schedule a sewer scope inspection, which uses a tiny, flexible camera to inspect the interior of your sewer line for common blockages like the ones listed above.

After the inspection, you’ll receive a report that details the condition of your pipes and offers recommendations for repairs. You’ll also receive tips for sewer line maintenance to help prevent future problems.

Fixing a Clogged or Broken Sewer Line

The best solution to fixing a clogged sewer line will ultimately depend on the culprit uncovered by your sewer scope. The most common fixes include:


If your sewer backup is related to waste, debris or grease that has collected in your main sewer line, the problem may be solved with a simple cleaning. This is best handled by a professional who has access to tools that can fully break down clogs and keep them from returning.


If your sewer is clogged due to a broken, misaligned or sagging pipe, it may be repairable without having to replace your entire sewage system. There are two types of repairs: traditional trenching or trenchless sewer repair.

Traditional trenching involves digging to the damaged section and then reburying it, while trenchless repairs don’t involve excavation. Trenchless methods are often preferred due to being less intrusive, more affordable and quicker, meaning you’ll spend less time without a working sewage system.


If your sewage system is beyond the point of recovery, a replacement may be needed. The most preferred replacement method is pipe bursting, which replaces damaged sewer pipes without the need to excavate. The new sewer pipe is pulled through the old pipe using a bursting tool that breaks apart the existing line. This can typically be done within a few hours and largely avoids disrupting your yard.

How to Prevent Clogged Lines

Perhaps the best solution for a clogged sewer line is to keep it from getting clogged in the first place. While you may not be able to keep a tree root from growing into your pipes, many other types of clogs are 100% preventable.

To actively reduce your risk of a main sewer line clog, you should:

  • Never throw any grease, fats or coffee grounds down the sink, or any other substances that could harden.
  • Make sure you clean pop-up stoppers and strainers frequently.
  • Make sure anything you put down the toilet is flushable. You should generally avoid flushing heavy paper products, even if they are labeled as flushable.
  • Always use plenty of cold water to flush food remnants away when using a disposal.

If you’re concerned your main sewer line might be clogged, it’s important not to delay the inevitable. Alpha Environmental has the extensive experience and latest equipment needed to make the process smooth and painless, from the initial diagnosis to getting your system back up and running. Contact us today to schedule your sewer scope inspection!

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Lake Oswego, OR
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Beaverton, OR
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