Safely Unclog Sewer Lines

Blocked Sewer? It could be a cross bore.

What is a cross bore?

A sewer cross bore is what results when a natural gas pipe is accidentally installed through the sewer pipe to your home. This can happen when a natural gas utility installs a gas service pipe, which runs underground from the street to your meter, horizontally using trenchless technology. Although trenchless technology allows for easy and efficient installation of gas pipes, when a sewer line is not marked properly, it is possible for the gas pipe to be installed right through a sewer pipe.

While you can have a cross bore for years without even knowing it, it can eventually cause your sewer to clog. Unfortunately, most machines used to clear sewer blockages can break right through an intersecting gas pipe, leading to a dangerous situation where gas can leak through the sewer pipe and into your home.

If you have a sewer clog, find out whether it is inside or outside your home.

  • If the clog is inside, it isn’t caused by a cross bore and you can proceed.
  • If the sewer clog is outside, there is a chance it is due to a cross bore. To avoid a potential gas leak, call a plumber, PSE&G at 1-800-880-PSEG (7734), or NJ One Call at 811.
  • If you don’t know where the blockage is, you need to find out before proceeding.

    Note: Even if you aren’t a natural gas customer, there is still a possibility that a gas pipe installed near the street was bored through your sewer line.

If you’ve already begun working on the sewer, look out for the following signs of a gas leak:

  • A hissing noise
  • A natural gas or “rotten egg” smell
  • Bubbling water in a toilet, sink, or other standing water


If you suspect there is a gas leak, evacuate the area immediately and take others with you. Do not use a light switch, your phone, or anything that can create a spark on the way out. Then, call 911 or PSE&G at 1-800-880-PSEG (7734) from a safe distance. For more information about gas leaks, click here.

For a video with more information about cross bore safety, click here.