I belong to a little 50 year-old brick bungalow in the midwest.
There's a small bathroom that's never been remodeled. A small sink with a U-trap, drain running horizontally thru tiles into the wall maybe 14" above the floor.
The portion of the drain that runs from the pvc U-trap into the wall is badly rusted. The drain runs very slowly. I've cleaned out the U-trap, run Drano thru, etc (no help).
I can't see anything of the sink drain from the basement. I figger it does a bend and runs (inside the wall and floorboards) into the toilet drain. But what do I know? :-)
At least part of the sink drain pipe will need to be replaced before long. I am sorta half-handy at plumbing. How might such replacement be accomplished?