Water sensitive urban design (WSUD) often consists of decentralized multi-functional technologies which are capable of producing both private and public benefits. However, private costs often outweigh private benefits, and therefore agencies must often provide incentives to encourage adoption of such technologies. Scarce resources also require cost-effective schemes. However, there is a lack of comprehensive analysis of the performance of incentive schemes to promote WSUD. In this paper, we develop an agent-based model to study the effectiveness of an incentive scheme to promote adoption of rain water tanks. Using a case-study based on Melbourne, we study how its cost-effectiveness changes with targeting different sizes of rain water tanks (2, 5, 10 kl) and different proportion of districts affected by heat stress. We observe that targeting smaller sized tanks promotes quicker adoption but is less cost-effective in terms of water savings and environmental services per dollar. Public agencies can use such information in developing more targeted approaches to promote WSUD technologies
