Main Sewer Clogs: Causes & Warning Signs

Main Sewer Clogs: Causes & Warning Signs

All of the plumbing fixtures, drains, and pipes in your home are connected to the biggest (and most important) piece of plumbing in your entire home – the main sewer line.

Between improper use of these fixtures, drains, pipes and many other outside factors, the main sewer line can take a beating. Eventually, the main sewer line can become clogged (or even collapse) to the point of needing serious repair or even replacement.

Knowing what causes sewer lines to clog and the warning signs to look out for can help prevent you from ever dealing with a major repair or replacement.

What Are the Common Causes of a Clogged Sewer Line?

Almost every homeowner has run into the unfortunate situation of having a clogged drain or a slow-running sink or bathtub. While a single clog can be a pain, it is typically easy to fix. Here are the primary indicators that a repair or replacement is required:

Severe Pipe Damage

When sewer pipes are broken or ruptured, the sewage will not properly drain through the system – leading to immediate and frequent backups. Common causes of sewer pipe damage include:

  • Sewer pipe rupture due to shifting soil, settling, increased traffic on the ground above or use of heavy construction equipment above ground
  • Corrosion of an older pipe, causing the pipe to break or collapse
  • Leaking joints where the seals between sections of pipe have broken, allowing water and sewage to escape

A Sagging Sewer Line

Bellied Sewer Pipe New Jersey - Belly Repair - Belly Replacement NJ

While this is out of a homeowner’s control, sagging sewer lines happen over time. This “bellied” pipe occurs when a section of the pipe has sunk due to ground or soil conditions.

The low spot in the line will begin to collect paper and waste – resulting in repeat blockages.

Tree Root Infiltration

How Tree and Shrub Roots Can Clog a Sewer Line - Eagle Service Company

Tree Roots Infiltration

Older sewer lines were sometimes constructed out of clay or other porous materials. In addition, the connections between the pipe sections were not as tight as today’s PVC pipes.

As tree and shrub roots grow, they search for sources of water. If they latch onto a sewer pipe, they will grow into the pipe in order to reach the water inside, which can cause the line to break.

Warning Signs You Might Have a Sewer Line Issue

If you are concerned about catching your sewer line issue before it is too late, we have gathered three warning signs you should look out for:

Frequent Backups in Your Drains

One advice is to steer clear of liquid “drain cleaner” and call a professional to check out that backed-up drain. If you have a drain that continuously clogs, especially in the lowest level of your home, it could come from a break or blockage in your sewer pipe.

Multiple Fixtures Are Clogged

Suppose you are not sure whether the toilet or shower drain keeps clogging because of an individual pipe blockage or because of a sewer line issue. In that case, an undeniable sign of a sewer line issue is when more than one plumbing fixture backs up at the same time.

Your Lawn Starts to Change

A sewer line typically extends from your home, through your front lawn and into the city’s sewage system. Head outside and see if you can notice any of these changes to your lawn:

  • If you have a break in your sewer line, you will see an indentation on your lawn
  • If you find a soggy patch of grass when it has not rained or snowed recently, it may be sewage from a broken sewer pipe

Strange Reactions When Using Plumbing Fixtures

The next thing to look for when you suspect a sewer drain clog is any unexpected or unusual reactions when using plumbing fixtures. You may have a problem if:

  • Flushing the toilet causes water to back up from your tub or shower
  • Toilet water starts to bubble. Should this happen, run water in the sink closest to the toilet for a minute or so. If the water continues to bubble (or rises), then it is not a fluke
  • Hearing a gurgling noise as the toilet flushes, the water in your bathtub or shower is draining. If you hear this, contact your local plumber


Let us know in the comment section below how you deal with main sewer clogs.

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