Cisterns were composition of reinforced concrete, fiberglass, Steel, cinder block or precast concrete. It was located either underground or in a concealed room. In order to store water in cistern, there has to be a gutter system and downspouts. This would help in directing the flow of water from roof to the reservoirs. The water stored in reservoirs could be used for plumbing.
Fortunately what Cyrex686 found was in a good condition to be reused. But on an honest note if you have improved and better technologies, why would you use some old technology?