waste venting/bubbling toilet

Jerome W. Young · 02-27-2008, 04:07 PM

I had a toilet today that was bubbling air through the trap almost splashing water out of the toilet when I started to drain the adjacent spa tub. both fixtures shared a waste vent. The tub had a 1.5 in. and it connected to a 3 in. that appeared to come from the toilet through the roof. I am not sure if the vent was blocked or what. Anyone know what is going on here?

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**Scott Patterson** · 02-27-2008, 04:57 PM

Originally Posted by Jerome W. Young

I had a toilet today that was bubbling air through the trap almost splashing water out of the toilet when I started to drain the adjacent spa tub. both fixtures shared a waste vent. The tub had a 1.5 in. and it connected to a 3 in. that appeared to come from the toilet through the roof. I am not sure if the vent was blocked or what. Anyone know what is going on here?

Sounds like the vent might be blocked. Could be several other things as well.

What happened when you flushed the toilet? Did it bubble at the tub or could you hear water from the drain?

**Jerry Peck** · 02-27-2008, 06:00 PM

Could be a vent blockage or a waste line blockage.

The vent could be something as simple as the plumber left the test ball in it and it is still inflated, blocking the vent, or, they may not have removed the thin plastic test cap. I've seen both more times than one would think possible.

Or, the test cap could have been broken out and knocked into the waste line instead of being removed, allowing the pieces to catch on something and partially block the waste line. When that happens, a lot of water draining at once places a lot of pressure into the waste line, and that pressure could spurt back up (just like you described).

That would be my two first guesses.

Have a plumber run a camera down the vent stack from the roof, they will see exactly what is where, if anything is anywhere. If nothing is there, then they may need to run the camera from inside (because the blockage could be between the drain and the stack).