Before you start looking for ways on how to unclog main sewer line pipes, you need to make sure that the blockage is within it and not just with one or two drains inside the house. For instance, if the water is slow to drain the bathroom but flows freely in the kitchen sink, then the clog may just be isolated to the piping network in the bathroom. However, if all drains in the home are all running slowly, then there is a good chance that blockage lies within the main sewer line. If several drains are backed up at the same time, then the blockage is definitely within your main sewer line.
Below is a step-by-step guide in unclogging your main sewer line. For this task, you’ll need a pipe wrench and a professional drain snake―also called an auger―which you can rent at a home improvement store. Read the instructions thoroughly before you attempt to clear the blockage.
Look for the Sewer Cleanout Line
As with any plumbing repair or installation project, it will be a good idea to turn off the main water supply before starting. Once you have done so, look for the sewer cleanout line, which is usually around the exterior of your home at street level. This access pipe should be jutting out some 6 to 8 inches from the ground measuring 3 to 4 inches in diameter with a screw-on cap.
Release the Water Pressure
If your drains have been backed up or have been running slowly for quite some time, then there might be a buildup of water pressure in the pipes. Using a pipe wrench, slowly loosen the screw on the cap. Once you feel that the cap is about to loosen up completely, open it up and step out of the way. Allow the pipe to drain all the wastewater before proceeding.
Feed the Drain Snake into the Pipe
Start feeding the drain snake into the main sewer line and work your way slowly into the pipe following the instructions that came with the machine. You’ll know when the end of the drain snake hits the clog as it will start to become harder for the line to move through the pipes.
Keep Running the Drain Snake
Once you see the water level inside the sewage cleanout pipe start to go down, the clog is slowly being cleared away. Keep running the drain snake through the pipes just in case there are any other blockages further in.
Pull Out the Drain Snake
Turn your main water supply back on and with a hose, spray water at full power down the cleanout line to ensure that water is flowing freely through the main sewage pipe. Pull out the drain snake slowly as you continue to spray water down the sewer as well as on the drain snake line to wash away any dirt and debris that may have stuck to it. After pulling out the drain snake line completely, replace the cap of the cleanout line and screw it back down firmly with the pipe wrench.
Keep in mind that some blockages to your main sewer line may not be cleared away easily such as tree roots or a collapsed pipe. For these kinds of blockages, you’ll need to hire professionals to fix the problem.