The answer to 'why is my sewer line slow draining' is that a slow draining sewer line is often caused by a blockage or buildup in the pipes. This can be due to things like hair, soap scum, grease, or even tree roots growing into the pipes. Symptoms of a slow draining sewer line include water draining slowly, gurgling noises, or even sewage backing up into your home.
If you have a slow draining sewer line, you may be able to fix it yourself using a plunger or a drain snake. However, if the blockage is deep in the pipes or caused by tree roots, you may need to call a professional plumber to use a sewer camera inspection and high-pressure water jetting to clear the line. In some cases, the pipes may need to be replaced if they are severely damaged.