Let me say at the outset that I am well aware that I can get only an educated guess in response to this posting, but I would welcome an educated guess or even pure speculation.
We live in a six-unit coop apartment building built in 1922. It's a very solid building which has been well-maintained and it in very good shape considering its age.
The apartments are identical in layout, two on each floor.
The fourth floor consists of six rooms which were once occupied by servant girls. It was a dormitory arrangement, with a shared bathroom at one end of the hallway, and a shared kitchen at the other.
Around 1950 these rooms ceased to be used for habitation and were converted to storage. At that same time, the hot and cold water pipes were cut and plugged.
To get to my question: What's likely to be involved if we reconnect the water supply? (To make the rooms habitable once again.)
The old pipes all remain in place, but I'm sure they are so corroded and rusted inside that replacement with copper would be essential.
I emphasize that all of the bathrooms are stacked in the same vertical configuration. I'm pretty sure that the old pipes have been replaced in the apartments through the years.
So I guess the second question is, is it likely that we can simply extend the pipes from the third-floor bathroom to the fourth-floor bath?
To repeat, I'm aware that I'm asking for a diagnosis done with a blindfold. I'm sure all sorts of issues, like water pressure etc., would come into consideration. But we do know that at one time the plumbing worked on the fourth floor, and we'd like to restore it if possible.