The transition towards the circular economy (CE) entails transformative and system-wide changes, implying involvement, alignment, and cooperation between all stakeholders at all levels. However, debate continues around how best to achieve this. Additionally, little attention has been paid to developing models for identifying and mobilising all relevant stakeholders to implement CE policies at the regional level. This study sought to remedy these issues by analysing the relevant academic literature and policy documents and making the first attempt to adjust existing models—not only for the purpose of stakeholder mapping, but also for the proposition of a living constellation of stakeholders who should be considered when designing the transition towards a CE in a regional scenario. The CE-centric quintuple-helix model developed and proposed here promotes the emergence and deployment of trilateral networks, hybrid organisations, and development/co-operation platforms. This model adopts a balanced, participatory approach that requires a new constellation of stakeholders. Its foundations are built on the traditional industry–government–academia nexus and enlarged by the inclusion of the civil society sphere and the environmental subsystem. The environment is represented as the nucleus of the model, inspiring and triggering actions by the remaining four subsystems. The model is then implemented into two European regions with CE initiatives (Spain and Greece) to demonstrate its practical application.

The circular economy (CE) was adopted in 2015 by the European Union (EU). Since its emergence, the CE has proved to be a remarkably powerful idea that has shifted the understanding of the economy, and consequently, it has shaped the EU's economic and environmental policies. The public policy literature theorises such shifts in collective understanding through the concept of policy learning, a process through which ideas are understood and adopted. Yet this literature lacks clarity on the factors that can explain policy learning within a policy community. We use the case of the EU's adoption of the CE to address this gap, exploring the factors that account for the EU's adoption of the CE from the policy‐learning perspective. We show how actors in the policy community have constructed, championed, supported and pioneered the CE and argue that these four factors have mutually reinforced each other, leading to policy learning and the wide acceptance of this idea within EU policy‐making. Revealing these factors helps advance policy learning theory and contributes to the CE literature and environmental policy and governance literature more generally by furthering our understanding of how and why certain policy ideas are adopted.

Cleaning wastewater and using it again for secondary purposes is a measure to address water scarcity in urban areas. However, upscaling of recycled water schemes is challenging, and little is known about the governance conditions which are required for this. This paper addresses this knowledge gap. Based on a review of governance literature we suggest that five governance conditions are necessary for a successful upscaling of recycled water schemes: (1) policy leadership, (2) policy coordination, (3) availability of financial resources, (4) awareness of a problem, and (5) the presence of a public forum. We applied these concepts in a case study on the upscaling of a recycled water scheme in Sabadell, Spain. We reviewed policy documents, conducted a set of 21 semi-structured interviews, and attended two policy meetings about the subject. Our results suggest that Sabadell meets the required conditions for upscaling reused water to a certain extent. However, a public forum is not well-developed. We discuss the implications of this and conclude with some suggestions for future research and some lessons for other cities that plan to upscale their recycled water schemes.

Cleaning wastewater and using it again for secondary purposes is a measure to address water scarcity in urban areas. However, upscaling of recycled water schemes is challenging due to the possible emergence of various barriers. Based on a review of the governance literature we suggest that a set of five governance conditions is necessary for a successful upscaling of recycled water schemes; (1) policy leadership, (2) policy coordination, (3) availability of financial resources, (4) awareness of a problem, and (5) the presence of a public forum. In order to elaborate on the practical relevance of these conditions we studied a recycled water scheme currently being upscaled in Sabadell, Spain. We reviewed policy documents, conducted a set of 21 semi-structured interviews, and attended two policy meetings about the subject. Our results suggest that Sabadell meets the required conditions for upscaling reused water to a certain extent. However, the presence of a public forum is lacking. We discuss the implications of the absence of the venue and procedures for public participation in Sabadell and how it could be strengthened. Following this discussion, we conclude with some lessons for other cities that plan to upscale their recycled water schemes.