Can you install working plumbing BELOW the sewer line? I'm looking at my
basement and wondering if I can add plumbing or not. I'm strongly
suspecting no, as the septic tank line is on the celing of the basement, so
any waste-water would have to pumped UP - plus the unsanitary potential for
downstairs sinks to turn into sewage fountains.

But I figured there's nothing hurt by asking.