6. Economic analysis
Rainwater harvesting systems remove some of
the demand for mains water and also release that
water for other increasing demands. They reduce
the volume of rainwater discharged and hence
may contribute to reducing flood risks and the
load on sewer systems. In addition, rainwater
does not require chemical, physical nor biological
treatment before use for most non-potable
demands. This makes maintenance of rainwater
harvesting systems generally easy and cheap [16].
The capital cost of rainwater harvesting
systems is highly dependent on the type of catchment,
conveyance, cistern or tank size and storage
tank materials used. In addition to the cost of
components, there is the cost of having the
system installed. The most expensive part of a
rainwater system is usually the cistern itself.
Rainwater harvesting systems designed as an
intergraded component of a new construction
project are generally more effective than retrofitting
a system to an existing building [14]. In
Jordan, the cost of a 30 m3 cistern is around
US $1500 to $2800, depending on the material
used. The cost of the equipment needed for a
basic household rainwater system starts at around
$500. Plumbing and fitting costs can exceed
1500, depending on factors such as soil type
(exca-vation cost) and size of the system (pipes,
screen, cost of concrete, steel, bricks, plastering
etc.).
These costs are estimated based on the current
market prices for the different components. While
discussing the cost of roof rainwater harvesting,