Horizontal Drain Line Un-Level
The Problem:
I just moved into a new house, and while doing the dishes, noticed that the kitchen sink backs up after running water for about 30 seconds. The sink does drain, but it is painfully slow. I thought it was a clog, so I tried Drain-O, and a pipe snake. Neither of those fixed the problem, so I disassembled the p-trap (on the double sink) and ended up replacing it.
An Observation:
Before closing on the house, I asked the seller to replace a leaky vertical drain pipe (thick PVC, maybe ABS) in the basement. I have a sneaking suspicion that the horizontal drain pipe (from the kitchen sink) ties into the vertical drain pipe in the basement. I think that when the vertical drain pipe was replaced, the new pipe was a fraction of an inch longer, which pushed the horizontal drain pipe off level. I think the kitchen sink backs up because the horizontal drain pipe slants towards the sink, not the vertical drain pipe, creating a back up.
The Question:
Can I simply remove a 1/2 inch section from the vertical drain pipe, in order to create the proper slant in the horizontal drain pipe, and correct the flow of water?