The answer to 'why is my sewer line making gurgling noise' is that a gurgling sound in the sewer line is often a sign of a clogged or blocked drain. This can be caused by a buildup of debris, grease, or other materials in the sewer line, which can restrict the flow of wastewater and create air pockets that make a gurgling sound.
Some common causes of sewer line gurgling include tree roots growing into the line, a broken or collapsed pipe, or a blockage from flushing non-flushable items down the toilet. The gurgling sound is typically heard when water is draining from a sink, shower, or toilet, as the air is forced back up through the drain.