Perspectives on Rainwater Harvesting: Perspectives on Rainwater Harvesting: Past, Present and Future Past, Present and Future David Butler David Butler Professor and Director, Professor and Director, Centre for Water Systems Centre for Water Systems University of Exeter, UK University of Exeter, UK The Future of Rainwater Harvesting in Buildings The Future of Rainwater Harvesting in Buildings University of Exeter, 21 University of Exeter, 21 st st January 2011 January 2011
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Perspectives on Rainwater Harvesting: Perspectives on Rainwater Harvesting:
Past, Present and FuturePast, Present and Future
David ButlerDavid Butler
Professor and Director, Professor and Director,
Centre for Water SystemsCentre for Water Systems
University of Exeter, UKUniversity of Exeter, UK
The Future of Rainwater Harvesting in BuildingsThe Future of Rainwater Harvesting in Buildings
University of Exeter, 21University of Exeter, 21stst January 2011January 2011
• Past
• Present
• Future
• What needs to be done?
• Conclusions
OutlineOutline
PastPast
• By no means a modern concept!
• Simple concept
• Systems found in:
– Israel, Africa, India, 2000BC
– Mediterranean area, 1700BC
– Petra, Jordan
• Decline of systems
• Uses of collected rainwater
PastPast
Rain was an important source of water in the ancient trading city of Petra,
Jordan, which supported a population of 20,000 in a place where just 150
mm of rain fell a year.
• Present day RWH remains a simple concept
• System Components
– Catchment
– Collection system (First flush diverter)
– Treatment
– Storage
– Pump
PresentPresent
PresentPresent
Indirectly pumped
Directly Pumped
OVERFLOW
100%
FILTER/SCREEN
PUMP
SEWER
SUPPLY
PresentPresent
PresentPresent
PresentPresent
BedZed, LondonBedZed, London
• Benefits:– Saves potable water (by displacing non-
potable water use)
– Saves energy/carbon (at least that associated with the displaced water)
– Reduces flood risk (especially summer storms & can be enhanced by better design)
– Reduces load on regional water resources and central water infrastructure (and potentially delays/limits expansion)
PresentPresent
Saves potable water (by displacing non-potable water use)
PresentPresent
Reduces flood risk (especially summer storms & can be enhanced by better design)