er, first, I live in a ghetto in Puerto Plata. I'm comfortable among the poor and I enjoy the constant life.
I've lived in various barrios in Puerto Plata, and exactly due to this I did not first understand why would you leave your furniture inside something you rent out. Now you responded, thank you.
Cistern - it's single gravity feed cistern on the roof for 4 apartments. Anyone of us could drain it just by leaving a tap open for a few hours or overnight. Unless it's setup with active monitoring (doubtful) or somebody checks it ever hour, I don't think anybody would know until it's all gone. Again, this is the ghetto.
That's not called cisterna, cistern is usually a concrete well below the house or the garage to store water. The tanks you refer to are called "tinaco". And again, I've lived in various locations throughout DR, and not sure why this "setup" has anything to do with this thing "ghetto" (barrio??)? It's pretty normal practice almost anywhere, unless you live in a place with real 24/7 pressurised tap water...
If I were you, I would try to get more tinacos onto the roof, the maximum I have seen is one tinaco for 2 apartments, best would of course be 1:1.