Toilet Bowl Mysteriously Drains

[MasterPlumbersKeymaster]

I have an upstairs toilet for which the bowl will mysteriously drain over the course of 4-6 hours.

I suspect that something in my venting is causing the the bowl to siphon dry but I am unsure about how to test this.

The flange seal does not leak and I have replaced the toilet. This toilet is situated close to the stack and where the stack exits the roof. A tub and sink share the same drain. The attached sink has a supplemental vent that exits the roof within 10 feet of the stack.

I have an identical toilet situated downstairs and connected to the same stack and drain – this one works properly.

Any ideas ?

Thanks.

[SylvanLMPParticipant]

Oscillation can cause this kind of phenomena.

Do you possibly have a down draft situation?

You could also have a mop string or dental floss or some other absorbent materials acting like a wick causing capillary action.

The easiest thing is to auger this toilet 1st THEN if nothing is found
check your vent location for possible down drafts.

[GuestParticipant]

Hi Sylvan,

Thanks for the feedback.

There is nothing in the toilet. It is brand new and I checked its trap before I installed it.

I don’t know what a down draft situation is – could you explain what is is and how you detect it.

Thanks.

[Author]

Posts