Abstract:
Rain Water Harvesting (RWH) to supplement service water is an important aspect of sustainable
development. As such, much research has been carried out on optimizing the system components of RWH
systems so that a maximum water saving efficiency (WSE) can be reached with a minimum storage capacity,
enabling the outlay on capital minimized. However, if RWH is to proliferate it should be able to operate in par
with centralized service water, supplying collected rain water to user points reliably. This is usually achieved by
pumping the collected rain water to service points utilizing electricity, which in fact could negate the positive
gains of RWH with regard to principles of sustainability.
By introducing a multi tank model, where a smaller tank is installed for each floor at its roof level in addition to
the main storage tank, a solution can be reached with superior system performance. In the model, the roof
collection enters the top most tank first and then cascades through multiple tanks in multi story situations, before
being collected in the main storage tank, vastly improving the overall energy efficiency of the system. The
model, not only addresses the space and structural issues of the building but also ensures that the aesthetics of
the building envelop is not disturbed due to smaller sizes of the upper tanks.
