I live on the ground floor of a three story condo building.
Occaisionally my toilet starts 'gurguling' and then somtimes the
gurgling is followed by rising water and soap suds.

When this happens, I am not using the plumbing or running water in my
condo at all. Normally, the toilet flushes and the tub drains very
quickly, so I do not think it is a drain clog issue.

My theory is that when one of my upstairs neighbors is doing laundry or
draining their tub, the water falls three stories and hits the bend in
the pipe underneath the my floor causing back pressure. Would an
appropriate fix to this be to add an offset by my ceiling into the
drain pipe to slow the water down?

Any other ideas as to what can be causing this - my theory could be
wrong... And what would some options be to fix this?

If your toilet is connected to a common drain I have seen the situation
where someone upstairs (perhaps several) dump enough water through the
drain to cause a suction effect that triggers the toilet to siphon.

If the toilet is filling up there is a drain obstruction on the sewer
main side of the pipe (or the pipe size is wrong) which allows the
sewer pipe to fill up. When the level is above your s bend the toilet
fills.

I am suprised you aren't getting water from the floor drain or the
shower or tub.

You need a plumber or your local plumbing inspector to look at the
setup and make suggestions.

You may be able to fit a backflow valve on the sewer line from your
apartment to the main.

A restriction in the vent stack will cause what you describe
Exactly the revent is supposed to keep this from happening. The
plumbing also might not have been installed correctly in the first
place. Another possibility is a restriction below the level of your
toilet that backs up only when there's a large load. The suds in the
water make it seem like a washing machine. If this has been happening
since you moved in you could have a case against the condo developer or
whoever sold the condo to you. Sewer gas escaping into your bathroom
would be a health hazard.
Richard

I like the backflow idea and I have to wonder why it isn't made code for
every floor in new construction.


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oups.com...
If your toilet is connected to a common drain I have seen the situation
where someone upstairs (perhaps several) dump enough water through the
drain to cause a suction effect that triggers the toilet to siphon.

If the toilet is filling up there is a drain obstruction on the sewer
main side of the pipe (or the pipe size is wrong) which allows the
sewer pipe to fill up. When the level is above your s bend the toilet
fills.

I am suprised you aren't getting water from the floor drain or the
shower or tub.

You need a plumber or your local plumbing inspector to look at the
setup and make suggestions.

You may be able to fit a backflow valve on the sewer line from your
apartment to the main.