I recently bought a new old house (in Madison WI). The house sits at roughly the top of a hill. Shortly after moving in, I noticed that sewage seemed to have backed up through the floor drain in the basement. I cleaned up around the floor drain and for a while nothing more happened. Then I noticed it again. It seemed to be at the time of a rain but since the house is at the top of a hill, nothing that would produce such a result was apparent.

Then I got a new toilet installed in the basement (previously there was only one on the second floor). When this was done, the basement floor was ripped open revealing a cast iron sewer pipe. Oddly the pipe did not follow a straight line from the floor drain to the clean-out at the end where it exits the house. Also the pipe seemed to be almost pitched backwards (I didn't think to get a level out and measure it) so that it would drain into rather than out of the house.

The plumbers cut out a section of the cast iron and patched in a PVC section with a T for the new toilet. They joined the PVC to the cast iron with big rubber radiator hose-like connectors. Then they filled over the pipe with dirt and concrete.

Everything seemed fine. Then I had my parents over who used the bathtub upstairs two days in a row (I use a shower at work). We left for the weekend and when I came back, the new toilet appeared to have backed up and there appeared to be darkness (indicating wetness) on the concrete right over the two places where the cast iron is joined to the PVC. The new toilet and adjacent new Stauder valve made lots of gulping noises when I flushed a few times.

I'm wondering 1) if you think it sounds like the sewer line is back-pitched and if perhaps some obstruction in the line "downstream" of the new T backed things up when the large amount of water from the bathtub was released 2) what you would do to remedy the situation?

"I'm wondering 1) if you think it sounds like the sewer line is back-pitched and if perhaps some obstruction in the line "downstream" of the new T backed things up when the large amount of water from the bathtub was released 2) what you would do to remedy the situation?"

I would call the plumbers back and inform then that the sewer backed up and the Fernco Neoprene Couplings they used to convert the cast iron to PVC don't hold water and are leaking and that you wish them replaced with Cast Iron to PVC No-Hub Clamps. While your at it have the sewer snaked and cleared plus checked for back fall. A No-Hub Clamp produces a stronger joint and secures the pipe from shifting. More questions? I'm as close as a click.
Tom