I can attest to the sewer line collapsing under a slab. Happened to us a month or so ago and it was a nightmare. Tear up hardwood, saw cut concrete, jackhammer up said concrete, haul it out in wheelbarrows from inside the house, lay pipe (not the fun kind), fill with dirt hauled in the house in wheelbarrows, pour concrete, let dry then replace cabinets and floors that were torn out by contractors. Then have fun replacing all the other stuff torn up during the process. And then get ready to cut a huge check. No help from insurance because it wasn’t an acute problem such as a tree falling through the house or a fire. Damn it felt good to write all of that. Sorry.