this system like rainwater catcher and piping system is very common as like the popular previous plumbing system that used in green architecture building concept.
but how to create a system that has strong feel of efficiency and raise people spirit in order to create new life habit of caring about a drop of H2O is what would like to achieved by this idea ..
so think about a building (a whole mass) in a city that it is a water plant, if you want fulfill water demand of a city; by a shortcut; first, it would be every corner of city is producing water. second, the building is fulfilling its own. third, there will be efficiency that'll generate surplus in the fresh water supply -> save it to reservoir (lake, river, manmade dam, etc.) and also we have more stock for the desalination plant.
-> think of the money of the future, not nowadays money.
investation in high-tech plumbing product is a little bit difficult matter to be realized. but think about little utilization of simple systems that'll create a great savings on water supply.
the system would be:
raincatcher = is a modular roof garden (pre-fabricated); it's size depending on building specs. its lightweight and easily maintained. and also its basic principle, cool the building, repel the sun heat and UVs.
piping system = use regular kind of pipe, filter, and work principle.
-utilize every drop of water - low use of fresh water (only to drink and take a bath)
-save the building
-save the city
-save the world