ABSTRACT
Retrofitting cities for sustainable integrated water management (SIWM) will involve new technologies at personal, building, neighbourhood and urban scales, which will also be associated with social, economic and institutional change. Retrofitting for domestic water efficiency involves installing water meters and water efficient devices, improving the efficiency of appliances and encouraging changes in water-using practices and cultures. Water efficiency is being encouraged through water company targets and building codes, but the volume of water saved by various measures remains highly uncertain. Rainwater harvesting (RWH) systems provide a distributed water resource that can be collected at building and development scale for non-potable uses. Successful retrofitting of RWH requires novel designs to reduce pumping energy and can be installed in roof spaces and on the outside of existing buildings, and a consistent approach to subsidies and wastewater service charges. Recycling water at an urban scale through planned indirect potable re-use (IPR) involves treating wastewater effluent using reverse osmosis and advanced filtration, then deliberately re-introducing it into water resources immediately prior to drinking water treatment. Planned IPR schemes in other parts of the world have met with significant public opposition, neces-sitating a move from expert-led decision-making to greater levels of public participation. Retrofitting cities for SIWM requires socio-technical change across all scales of urban activity. Conventional models of expert-led, centralised provision of water and sanitation infrastructure are undergoing significant reform to address the complexity of new arrangements and changes in the flows, institutions and cultures of water in cities.
