Water and sewage drainage is also a big deal. Almost impossible to retrofit for 150 bathrooms, around the buildings, when you originally had 20, around the elevator columns.
Source: I have a friend that ran industrial plumber crews in NYC for 40 years.
We don't like to talk about pee and poop, but they are a really important consideration, in almost any human venture.
I don't buy it. Pipes are IMPOSSIBLE to increase the size? Or at some point you hit some city service with no motivation to actually provide service/infrastructure and fix the problem at that end?
I wonder if you can have septic storage for excess flow, that then releases overnight when people aren't using it. Simply time shift the maximal flow periods and maximize the flow utilization of the existing stuff.
Maybe you can use pumps to force more liquid through the pipes faster.
Or you simply put in 80 instead of 150, and find other uses for the space.
Source: I have a friend that ran industrial plumber crews in NYC for 40 years.
We don't like to talk about pee and poop, but they are a really important consideration, in almost any human venture.