3 years experienced plumbing apprentice trying to figure out what the hell was done here.
What about it?
Was sent to a house because the toilet was flushing slow. Determined that either septic is full or there's a main line clog as every fixture is backing up. Went under to get a look at the waste and found this. It's the shower drain. No trap and that line is 2" pvc. So my best guess is that they installed a 3" shower flange and obviously didn't care to fix their mistake because they didn't want to rip out all the vinyl? So they just butted the 2" pvc all the way inside the 3" flange?