There is a need to re-configure current urban water systems to achieve the objective of sustainable water sensitive cities. Stormwater represents a valuable alternative urban water source to reduce pressure on fresh water resources, and to mitigate the environmental impact of urban stormwater runoff. The selection of suitable urban stormwater harvesting sites is generally based on the judgement of water planners, who are faced with the challenge of considering multiple technical and socio-economic factors that influence the site suitability. To address this challenge, the present study developed a robust GIS based screening methodology for identifying potentially suitable stormwater harvesting sites in urban areas as a first pass for subsequent more detailed investigation. The study initially evaluated suitability based on the match between harvestable runoff and demand through a concept of accumulated catchments. Drainage outlets of these accumulated catchments were considered as potential stormwater harvesting sites. These sites were screened and ranked under three screening parameters, namely demand, ratio of runoff to demand, and weighted demand distance. The methodology described in this paper was successfully applied to a case study in Melbourne, Australia, in collaboration with the local water utility. The methodology was effective in supporting the selection of priority sites for stormwater harvesting schemes, as it provided the basis to identify, shortlist, and rank sites for further detailed investigation. The rapid identification of suitable sites for stormwater harvesting can assist planners in prioritising schemes in areas that will have the most impact on reducing potable water demand.

no clear guidance available to select the best SWH site out of many potential sites in the area. Existing selection approaches are ad-hoc and use subjective knowledge of urban water managers to shortlist the potential SWH schemes. Apart from site selection, SWH infrastructure planning is complex and dynamic, where systems are expected to achieve several objectives such as maximizing the reliability of supply, minimizing the public health risks, minimizing the impact on environment and minimizing the supply cost. In this context, the focus of urban water managers has shifted to address these real-world problems through Multi Criteria Decision Analysis (MCDA) which is capable in providing multi-objective assessment of SWH systems and options (Brans 2002; Kodikara 2008). MCDA is a widely used decision making tool in water resource management decision making including in SWH systems (DEC 2006; Taylor 2005, Zardari 2015). MCDA can provide decision aid for SWH systems decision making for their option assessment for selection under conflicting objectives along with different interests of stakeholders. For example, a SWH project may have an objective of minimizing the project cost, while at the same time trying to improve the aesthetic and social values for community welfare which may increase the cost of the scheme. The MCDA methods can also assist decision makers to account for the inherent conflicts and trade-offs among such objectives and to rationalize the comparison among different decision options (Kodikara et al. 2010). Currently, there are various assessment frameworks developed for the evaluation of urban water servicing systems in the literature (

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