Hiya rat people!!!
Thanks for all the advice so far. Here's the (dumb, vexing) situation...
We found a second plumbing comapany nearby--very large company (~100 employees) and all five star Yelp reviews (hundreds of them FWIW). They sent one of their lead plumbers--guy seemed to really know his shit. He and a trainee plumber came out in Mid-November for the afternoon.
He removed about an 18x18" piece of drywall opposite the toilet, in the bedroom wall. He found five copper pipes that had been cut and not re-sealed by a previous re-pipe job. He filled them in with concrete, but was doubtful the rats were coming in through those pipes. I asked whether he needed to look at pipes further up in the wall, and he said no—absolutely not. He then replaced drywall—did a pretty good job with it.
He then opened a little door in our closet wall that leads to the bathtub area—saw nothing. Then he ran the camera from the roof vent pipe all through the sewer line system. His report said: “Ran camera through a 2 inch vent on the roof inspected sewer line for visible cracks or openings on vent vent looks good no cracks visible or broken pipes.” He assured me that the entire sewer line from the roof to the municipal sewer (or watever it’s called) is fine, great, and not in need of any work.
He assured me that the rats are not coming in through the plumbing.
We were very satisfied with their work and the price was reasonable for all that = 450$ (Better than the 750$ the other crooks charged me for a one hour smoke test)
Couple weeks later, about 8PM I hear what sounds like a large animal (possum or larger) in that wall again. I bang on the wall and it seemed to scrare it away. It came back the next night, same thing. Then a few weeks go by and nothing. Now, I’m hearing it/them again, but the banging on the wall does not scare them away. They seem to show up around 8PM (wake up time?) then possibly leave, then are active again around 4AM.
Called the exterminator out again and he said that these cameras the plumber used are pretty useless for finding rat ingress points. He pointed out that we have a metal pipe into which runs a larger diameter plastic pipe near the roof. He said the rats could come in from the sewer, all the way to the junction of those two pipes and, if there is any weakness or gap, come in there. That is the area where we hear the rats! He said that a camera would likely not see any gap between these two pipes—AND the pipes apparently take eight hundred million turns and the camera likely is not flexible enough to go through all of them.
He advised to have the plumber come out again, rip the shit out of the wall and find the gap. Then he said we should consider a sewer backflow valve. He said this solution is very well documented to work.
I asked the extreminator to write this shit down in detail so we could give it to the plumber—and I will not have to convey it all myself. He basically refused and said “just keep it simple—there’s a hole in the pipe in the wall. Open it up and fix it” Pissed me off: Even my fkn lawyer who charges me 500$/hour is HAPPY to write down anything I ask for (of course he charges me for his time), but this exterminator refuses. I ALSO asked him if we could set up for both the plumber and him go be here at the same time—or at least talk on the phone—so, again, I don’t have to try to be the middle-man. He doesn't want to do that either.
Hence, he seems like a good exterminator, but his unwillingness to write things down or to communicate with the plumber really puts me off.
At this point, I think I will call the plumber and discuss—but as far as the exterminator, I am very much inclined to just call in a rat expert. There are a few in this area that get hundreds of five-star Yelp ratings (for whatever that’s worth!)
Anyway, I’m stuck in the middle of course! Plumber thinks they're coming in from outside; Exterminator thinks they're coming in through sewer line.
Thanks for reading this and for any advice. (Be happy you’re not me--what a vexing problem!)