what is up with this drain backup
I have attached a diagram of the system. The basement sink drains very very slowly, and gurgles loudly when using the upper sink.
Actions taken so far with no success:
- snaked from basement sink to where the pipe goes into basement floor (at the red marker - i cut into it at this point and verified that there was no clog upstream to sink)
- snaked downward 20' to 25' below ground with my 3/8" snake, came up with a bit of hair, but can't be sure if there is a clog down there.
I am hoping the problem is a clog in the vent, otherwise it must be a clog underground??...
thanks for your help!