The pipes that connect your home's plumbing to your septic tank or the city sewer system need to have a consistent downwards slope. The sewer line relies on gravity to successfully move waste through the pipes. If one section of pipe sinks lower than its adjacent sections, it results in a sagging sewer line. Waste will be required to flow uphill through one section of your sewer line, which often results in slow drainage and frequent clogs. If you've been frequently encountering these plumbing problems, read on to learn how to tell if you may have a sagging sewer line and how you can fix it.

What Causes a Sewer Line to Sag?

A section of sewer line can begin to sag if the soil underneath it shifts. When a sewer line is installed, the plumbing contractor compacts the soil on the bottom of the trench in order to prevent it from shifting. In some cases, sand or gravel is added for extra support.

Even with these precautions, however, the soil underneath the sewer line can still shift and create a space underneath the pipe. Once this happens, the weight of the soil on top of the sewer line will push that section of pipe downwards into that open space, causing the sewer line to sag.

How Do You Know if You Have a Sagging Sewer Line?

If your sewer line frequently clogs, it may be caused by a sag in the sewer line. In most cases, water pressure in the sewer line is capable of pushing water out of the sagging area and further along the pipe. However, solid objects such as toilet paper are heavier than water, so it's more difficult for them to be pushed out of the sagging section of pipe due to water pressure. As a result, solid objects will accumulate in the sagging area. They'll form a clog that needs to be removed with a pipe snake.

How Do You Fix a Sagging Sewer Line?

In order to fix a sagging sewer line, a plumbing contractor will first dig a trench around the affected area. The sagging section of pipe will be removed and then the soil in that area will be re-compacted. Afterwards, a new section of pipe will be installed. With additional support provided by re-compacting the soil, the new section of pipe will be protected against sagging in the future.

While trenchless sewer line repair is very useful for fixing other types of sewer line problems, such as cracks or tree root intrusions, it's an unsuitable method for repairing a sagging sewer line. Placing a new pipe within the old one won't fix the slope of the pipe, and you'll still have a sag in your sewer line. Digging up your sewer line and fixing the slope may be invasive, but it's the only way to truly fix your sewer line.

If you think that your sewer line is sagging due to the frequent clogs you're experiencing, call a sewer line repair contractor to have your pipes inspected. Sagging sections are easy to spot with a pipe camera, and you'll be able to quickly know if your sewer line is sagging. If a sagging area is found in your sewer line, it's a good idea to have it fixed quickly—if the soil keeps shifting, the pipe may break entirely and prevent you from using your home's plumbing.