re: Replacing old cast iron drain pipes

started with a washer drain line backfilling. this is the drain line for the washer, dishwasher and sink, that all come together and ties into the rest of the plumbing in the house. I looked at the disclosure docs from the closing and it looks like a good portion was replaced on the side of the house with the showers and toilets along with the sewer main connecting to the city. We sent a snake down there a day or two later after not using the washer, dish washer or sink and discovered the bottom of these pipes were completely gone.

The plumber cut a section of the patio out and hired some guys that do specifically this. They have tunneled under the slab ~20' found more bad pipe and have tunneled from a different area without breaking and concrete another ~20'

It's all got to go. If I leave it alone at this point its just going to get worse,