Decentralized and user-led approaches to rainwater harvesting and greywater recycling: The case of Sant Cugat del Vallès, Barcelona, Spain

Harvested rainwater and recycled greywater are becoming new sources of water for urban areas. Together with demand-side management, their use can help to ease the pressure on conventional water resources. In the Metropolitan Area of Barcelona, several municipalities have passed directives regulating the installation of rainwater harvesting and greywater recycling systems in new buildings. Users (i.e. citizens) are responsible for the systems' management and performance, assuming the control and the burdens over these alternative water supplies. In this paper we focus on the case of Sant Cugat del Vallès, a wealthy suburban municipality pioneer in the promotion of rainwater harvesting and greywater recycling in residential buildings. We provide a succinct description of the evolution of the trajectory of alternative water sources in this municipality since 2002. We also assess qualitatively the performance of rainwater harvesting and greywater recycling, pointing out both successes and pitfalls. The sources of information include interviews with environmental managers of the City Council; meetings and workshops with stakeholders; and visits to systems. This research suggests that political will at the local level as well as users' acceptance are essential for the correct operation and proliferation of these technologies. However, indirect factors such as droughts and water price hikes can make them more economically viable and socially desirable.