Den wrote:
Joseph,

Can't get up there today ... but from memory there are at least three.

A thought ... this all happened when there was no water being emptied
into the sewer system ... and about two hours since the any volume of
significance (shower + toilet) had been emptied.

Why would this happen when the system was quiescent?

Cheers

D


It could have been from the outside (like a neighbor), but a good vent
system should have allowed it to escape to the outside without any notice
from you.

This may not be the best test, but you should be able to run a hose down
there full force for some time without any backup. You would need to check
each vent.

--
Joseph E. Meehan

26 + 6 = 1 It's Irish Math