Balky basement toilet in new house

[dg_moore]

I have a toilet adjacent to an unused bathtub in my basement. Every few weeks the toilet fails to flush even though it is not clogged. I reported this to the plumbing subcontractor and they advised me to run water in the tub for a few minutes. I have been doing this regularly, and after the water runs for several minutes a large quantity of air bubbles up through the toilet outlet/throat. After this settles down the toilet flushes normally and continues to do so until the next occurrence in a few weeks.

Clearly this has something to to with the vent, but I remain curious

• a) what causes the toilet to periodically fail to flush;
• b) why the air bubbles up through the toilet after water has been run in the tub;
• c) why the toilet resumes flushing after performing this procedure.

This is not something I'd want to dig up the basement floor to fix, but I'm interested in finding out what is happening.

 

[PlumberMike]

For the answer to A & b thats a venting problem. for the answer for C that’s because the toilet got air into it and started to flush. check to see if there is a vent and if there is check to see if it’s clogged