Your main sewer line, which delivers all of your waste and wastewater to the public sewer system, is located deep below ground. Though this pipe is not in your line of sight like a toilet or a sink, the line certainly requires some care and attention. Because of the location, major problems with your main sewer line are not easy to repair, so it’s important to catch these problems early. You’ll also want to do some preventative maintenance to keep your line in good shape.

What Are The Common Problems?

The most common problems homeowners have with their main sewer line include the following:

Collapsed Pipes

Sometimes, shifting soil may crush your main sewer line or cause it to collapse in on itself. This can also happen if something very heavy, like a dump truck, is unknowingly placed over the main sewer line.

Tree Root Growth and Clogs

Tree roots are drawn to moisture, so if there’s even the slightest crack in your main sewer line, roots will grow towards the pipe and begin working their way into it. Items like toilet paper and feminine hygiene products will then get stuck on the roots, causing clogs.


This problem is especially common in cast iron sewer lines, which is the most common type used in homes after 1970. Though cast iron has many advantages as a sewer line material (it’s less prone to tree root invasion and collapse), rust and scale deposits can form on the insides of the pipes. These deposits can then grab onto solid materials and contribute to clogs.

What Signs Indicate You May Have a Problem?

The signs of a main sewer line problem are very similar regardless of which of the above problems you’re dealing with. They include:

  • Sewage backups into toilets and sinks
  • Slow drains throughout your home
  • A sewage odor coming from your drains

These problems may appear and slowly become worse—or they may appear, disappear, and then reappear in a cyclical pattern. The latter cycle happens when a clog forms from solid materials getting stuck on roots or corrosion, the clog is naturally freed, and then a new clog starts to form.

What Can Your Plumber Do?

If you suspect your main sewer line may not be in the best shape, your plumber will start by sending a special camera down into the line. This allows them to visualize any roots, corrosion, or collapsed portions.

In the case of tree roots, your plumber may use a special rotating auger with a blade on the end to cut away the roots. An herbicide may then be placed in the pipe to reduce further root growth.

If the sewer pipe is collapsed or badly corroded, the best solution is typically to replace the damaged section of pipe. For minor corrosion, your plumber may use a powerful water jet to remove the rust and scale deposits and smooth out the inside of the pipe, preventing future clogs from forming.

How Can You Better Care For Your Main Sewer Line?

If your sewer line currently seems to be in good repair, then you should take some steps to keep it that way. Here are a few good ideas:

  • Avoid planting trees or large shrubs anywhere near your sewer line.
  • If you have a cast iron sewer line, have it water-jetted about once a year to keep corrosion at bay.
  • Avoid parking on top of your main sewer line, and never place anything heavy on the ground above it.
  • Try not to flush anything other than toilet paper and human waste.  If you do have some root growth or corrosion in your sewer line, items other than toilet paper and waste are more likely to cause clogs.

Your main sewer line may not be a plumbing component that you think of often, but it is an important one. Take a few minutes to check up on your main sewer line’s health, and contact a local plumber if you suspect your line is not draining as well as it should.