On May 25, 1:21*am, Comboverfish wrote:
On May 24, 9:35*pm, DerbyDad03 wrote:





On May 24, 10:27*pm, "Don Young" wrote:

"DerbyDad03" wrote in message

....

My basement toilet has started to erupt as a bubble of air blows water
up and out. As far as we can tell it happens on a random basis. We'll
lift the lid and the underside will be all wet. My daughter was
walking through the basement and heard - well, she heard whatever
sound a large under water bubble would make.

Let me describe the drain and vent set-up:

First: This toilet has been installed for as long as I have lived in
the house (25+ years) and has never bubbled before. Nothing has
changed as far as the venting or drains. The toilet flushes fine and
all other fixtures drain normally.

Second: This bathroom is in the corner of the house where all the
drains meet under the slab just before leaving the house. The toilet,
shower and sink in this bathroom are the last set of fixtures before
the drains leave the house. The toilet is before the shower and sink
which wye into the main sewer pipe about 3 feet from the exterior
wall. There is a clean-out just inside the exterior wall under the
sink.

Third: My house has only one vent - the soil stack, which is in the
opposite corner from the bathroom. No fixture in the house has it's
own vent, and never has. Right or wrong, this has never been an issue.
All fixtures have always drained properly.

So, based on the information above, can someone explain why my toilet
has suddenly started erupting like Mount St. Helens?

Thanks!

I would think most likely a partial obstruction has developed, most likely
somewhere upstream toward or in the vent. Check the vent for debris. A
properly installed and working vent is intended to prevent this exact thing.
Flushing a toilet injects a large slug of air into the line and if it does
not escape out the vent it will pressurize the line and blow water out of
the toilet and other traps.

Don Young- Hide quoted text -

- Show quoted text -

Interesting.

One answer was slug of water hitting an obstruction beyond the toilet
and the next answer is a trapped slug of air before the toilet.

P.S. since posting my original post, I heard the BbbblewwERP and then
the sound of the upstairs toilet flushing, at least I know I should be
able to reproduce the problem.

What if I opened the cleanout in the basement, essentailly venting
that toilet. If the bubble still occured (or didn't) would that help
indicate where the problem was?

If this is a standard cleanout at approximately. waist level (no pun
intended), The water isn't going to have the impetus to travel 3 feet
up the soil stack, verses just slowly making it's way out to the
sewer. *It sounds like you have a few roots growing into the clay or
cast lateral, and they are partially obstructing waste paper etc.
Large quantity drain dumps like a toilet or a clothes washer during
spin/drain should yeild the same phenomenon. *Whatever you do, make
sure that the above toilet isn't serviced by the same stack with the
cleanout, or you will have one big mess if you flush it with the
cleanout off!

Not doubting you, but if the vent was clogged, wouldn't it cause
problems with other drains?

The reason it's happening at your basement toilet is that it is the
lowest point in the drain system that has an air trap in it (cast into
the toilet bowl). *The gallon or so of water held above this air break
is why you *hear* the gurgling of air escaping. *You won't hear it
with other "vented" drains like the floor drain or shower/tub because
there is no above ground water to push out of the way in these cases.- Hide quoted text -

- Show quoted text -

If this is a standard cleanout at approximately. waist level

Cleanout is at floor level.