My home is approaching 50, and although we have a full basement, we also have a bathroom down there, and all the plumbing eventually runs under the concrete floor.
About 5 years ago, the area was converted to public sewer from septic, as was our house. In most situations they simply run a new line out the front wall of the basement and straight to the main sewer line, but in my case they had to use all the existing drain piping, and simply pulled the septic tank and ran a new sewer line from the end of the old pipe, and around the back of the home to the front, about 200’.
This all happened before we bought it, so we did not have to pay for all this work. I wonder, though, if any of the original pipe under the house was likewise inspected before someone decided to reuse it.