Sewer line bellies are a common occurrence when dealing with cast iron or clay sewer pipes. A sewer line belly is essentially a sag in your sewer pipe that allows sewage water to sit in the line and as a result sediment will restrict the normal sewage flow.
The sewer line belly may occur at any point thought-out your sewer line and in many cases you may several bellies. A normal sewer line should run on gravity allowing the sewage to flow downwards, similar to a slide. When you have a sag or belly in the pipe the sewage will collect in this area and will have to flow back up before running on gravity like a sewer line is supposed to.
There are a number of reasons why bellies may occur. The most common reason is if the sewer line was installed by a non-licensed or inexperienced plumber. The average handyman may be able to lay pipe and put it together however, there are many other variables to consider when measuring for proper pitch for the entire length of the sewer line. It is also important for the plumber to understand the plumbing code, what is allowable and even the possibility of too much pitch.
A belly may occur if the pipe was not installed with proper support, this may mean that the soil was not compacted properly, the pipe may have been installed on sludge or without the proper pitch.
It is also possible for a belly to occur for reasons out of everyone’s control such as tree roots shifting the soil or pipe, earthquakes or a change in temperature which forces the grounds to shift.
The best way to avoid a belly is to make sure that your sewer line is installed with proper support, quality soil and compaction. It is also extremely important to make sure that the pipe is installed with the proper pitch from the beginning which will allow your sewage to flow on gravity as it is supposed to.
The best way to investigate and determine if your sewer line has a belly is to complete a professional camera inspection. The camera will allow the technician to take a close look at the inside of your sewer pipes which will display how the sewer line is running. If the sewer line does have a belly the camera will clearly display the location of the problem and what is required to resolve it.