I discover a large puddle of water on the laundry room floor that is leaking through the ceiling. The upstairs bathroom is directly overhead. A plumber is called in to diagnose the problem.
The plumber suspects that the house has several other plumbing problems, and I agree to let him cut some small inspection holes in the drywall.

He discovers that the downstairs toilet, sink, tub, shower, and laundry tub are all plumbed without venting pipes.
He also discovers illegal electrical wiring , and six additional water leaks inside the walls.
The water damage from the upstairs bathroom leaks has caused the drywall of the laundry room ceiling and walls to crack.
The plumber discovered more problems beneath the kitchen sink.
Most of the water lines were pieced together with alternating scraps of soft copper pipes (instead of rigid) and radiant floor heating hoses (instead of pex pipes). All soldered plumbing unions were done in place, badly burning the framing next to them.

The upstairs bathroom faucet was missing parts for the drain lever.

The water pipes were never fastened to the house framing.

At this point, the plumber informs me that all of this work was likely done by the same person, illegally, without a permit, and that all of it is failing. Both of my bathrooms and kitchen become un-usable. My house had been flipped by somebody who cut an obscene amount of corners.
My realtor also visits the house to see the problems for himself. I’m informed that there are no lemon laws for houses and the sale cannot be reversed. I’m not sure what to do.