This is where I was working for too long today. The white pipe is the drain for the bathtub in one of the bathrooms. It is of ‘singular’ construction, and not particularly apt for moving water out as it has almost no drop due to length of the down pipe. The execution of the P-trap displays a lack of measurement that is common when you are installing something under the house.
I have a picture because I took my camera to the site in hopes of a cat picture [no luck], and got tired of describing things to the two guys who didn’t want to crawl under to see the situation for themselves.
We haven’t quite figured out what all of the blocks are supposed to be supporting, It would make more sense to put them under the joists if the floor is sagging. With this house, who knows…