Q: Good Morning Ben, My son had a house built in Savannah Georgia and sent me this question. Thank you, John
What makes a toilet keep bubbling, when the shower is used, or water is going out of tub? I have a video file of what is occurring, but I think it is too big to send to you.
A: Hi John,
Very common question and I'm so glad you asked. I talked to my "gurgle expert" Don Somderdyke, Peter Somerdyke Plumbing, in Grand Rapids, MI 616-977-3377 and Don has this insight.
It probably is some sort of partial obstruction in the main drain line servicing the bathroom. The assumption we're making is that along with the gurgles/bubbles that the drain also slow drains. Otherwise it could be a sag in the line that's holding water. In either case what could be happening is the drain water fills up the entire drain line and the air that's in the line needs to find an escape route so it bubbles it's way back up from whence the water came. It also can create a siphon in the toilet causing it to bubble.
Next Step: Remove the toilet and snake/clear the drain line of any accumulated debris. Sags in the line can only be fixed when the pipe is exposed. In other words tearing up the floor or ceiling below and may not be necessary.
If you don't do anything...at least you have a good idea of what's happening now. Take care John and thanks for the note.