Taking place in modern day, in a complex of buildings all connected together and to nothing else.
I checked google with "Currents in water pipes" "Water currents in water pipes" I don't know what else to look up, everything that comes up is about electrical currents, and that's not what I'm looking for, I'm looking for the WATER current inside. Like I've seen cities put turbines in water mains, but in a house's or apartment's pipe's, or in the situation I've set up above where the complex is set up so it's cut off from the outside world and the water is pumped from a storage tank, if I put fans in the pipes, would they spin? If I tried to send something through the pipes would a current wash it away in direction of where someone has a tap open or flushed a toilet? What about if all the taps and everything was off, would the water stagnate in the pipes, even if there was a water pipe from the storage tank with a pump going to the complex?
I think I need help from a plumber!!!