Starting on pg 338. Mainly to do with soil, but also has info on water quality.
https://books.google.es/books?id=UTIduL47SeEC&pg=PA337&lpg=PA337&dq=madrid+sewer+system+map&source=bl&ots=lKLY53eOOw&sig=fnN145q0E1MrwKou6JOjjuQMVac&hl=en&sa=X&ved=0ahUKEwjT6quGgInNAhUBPhQKHUfYAPUQ6AEIMjAD#v=onepage&q=madrid%20sewer%20system%20map&f=false