International Rainwater Catchment Systems Conference
Catchment: An Answer to the Water Scarcity of the Next Millennium."
Petrolina, Brazil - July 1999
Section 4: Technology of Rainwater Catchment Systems
Affordable Roofwater Harvesting in the Humid Tropics
Terry Thomas & Dai Rees
DTU, School of Engineering, University of Warwick
The relatively high cost per household of installing full
domestic roofwater harvesting (DRWH) has resulted in its take-up being largely
limited to areas of especially high water stress or where DRWH is subsidised.
The paper discusses various ways of attaining satisfactory benefit:cost ratios
in areas where DRWH is not the only water supply option, for example by adopting
partial or seasonal supply and by minimising 'first cost' (generally
construction cost) at the expense of raising subsequent costs. As water storage
accounts for the bulk of expenditure on most systems, the paper then focuses on
means of minimising the construction cost of storage tanks in the size range
1000 to 10000 litres. Best cost-cutting practices with respect to both surface
and underground tanks are reviewed. An approach of separating the 'structural'
and the 'water-proofing' roles of construction materials is proposed and
applications of this approach to both sorts of tank are examined. The paper
will particularly reflect experiences in South Asia and East Africa which are
the geographical focus of an ongoing 4-country DRWH research programme funded
by the European Union.
PDF of full document (8pp, 76kb)
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