The answer to 'why is my drain making gurgling noise' is that the drain is likely clogged or there is a blockage in the plumbing system. Gurgling noises are a common sign of a clogged drain, as air is being forced back up through the drain due to a blockage further down the pipe. This can be caused by hair, soap scum, food particles, or other debris building up over time.
The gurgling noise occurs when water is trying to flow down the drain but is being obstructed, causing air to bubble back up through the drain opening. This can happen in sinks, showers, bathtubs, or other drains in the home. If left untreated, a gurgling drain can lead to more serious plumbing issues like a complete clog or even a sewage backup.