The gurgling sound that you hear your toilet produce can be happen for several different reasons. It could mean that there is a problem with your sewer line such as a problematic drain vent, a partial clog or blockage along the sewer line, or a faulty septic tank.
Understanding the reason for the gurgling sound that you hear from your toilet
Clog or obstruction along the main sewer line: As we use the toilet day in and day out, some waste matter such as toilet tissue or small chunks of soap could accumulate along the sewer line. Eventually, this accumulation together with hair, grease and other trash can cause a clog or blockage that will slow down draining and impede the air flow along the sewer line. When air is not drawn from the outside to flow freely along the plumbing and sewer line then you will hear that gurgling sound.
Improperly installed vents or blocked vents: The gurgling sound that you hear from your toilet could be the result of an incorrectly installed vent. A vent is a tube or pipe line that is connected to the main sewer line. It stretches to the outside of your house through the side or roof. The purpose of a vent is to create a suction-like action that pulls water through the drain as it is flushed through the pipes to make it flow easily towards the sewage line. An improperly installed vent means less air and less suction, thus the gurgling sound. A blocked vent also has the same effect. It also is responsible for sewer gases being vented out.
Full septic tank: A full septic tank has less space for air in the septic tank and so does a totally clogged septic tank, this could be another reason why you hear the gurgling sound from your toilet. This is a very serious problem since it could result in an overflow.
Whatever the reason is that your toilet is producing the gurgling sound, having it inspected and the problem remedied by professional plumbers is important. You don’t want a toilet that has backflow into your house.