Water scarcity and security drive attention to water reuse in policy and business. However, water reuse may generate new water loops and challenge water governance with new and different types of water, risks, involved actors, and responsibilities. These challenges demand robust institutional arrangements related to water governance. This article assesses the institutional arrangements associated with four case studies in Spain, Italy, Croatia, and Israel. The findings reveal that the more diverse the water uses and users, the more challenges and risks, particularly those associated with institutional arrangements such as quality standards, sanctions, and conflict prevention, are likely to emerge. The weaknesses of governance models and regulations to deal with changes, uncertainties, and public resistance call for special attention to the design of the institutional arrangements before the adoption. Independent of the type of technology adopted, governance may be improved by ensuring internal and external water monitoring; integrating water management with spatial concerns; improving training, expert engagement, and civil society awareness; and reducing water reuse costs. In addition, alternative models that guarantee the efficiency of governance in attaining objectives and assuring the participation of new water users in the management of water reuse loops may also improve governance.

Estuaries are one of the most productive and complex types of ecosystems supporting a wide range of economic activities. Departing from a set of governance problems and emergent goals, such as sustainability or climate change adaptation faced by an estuarine case study area, Ria de Aveiro, in Portugal, this article assesses the adequacy of alternative governance models under the existing water resources legal framework and traditional political culture. It shows that apart from the centrally-based compliance model, all other alternatives require high degrees of institutional reforms. Moreover, although the model based on a dedicated new agency, long preferred by many users of Ria de Aveiro, is the most understandable and focused, it does not assure the pursuance of adaptability or collaboration, which are considered essential for estuary governance. As it relies on collective action and multi-level and multi-agent contexts, estuarine governance may require a new institutional design. Where one begins a process of institutional change, however, is not a simple issue to address and demands a deeper analysis, particularly on the types of required institutional changes, as well as on their impacts on policy and decision-making outcomes over estuarine environments and associated socio-ecological networks.

The transition towards a Water Circular Economy (WCE), in the sense of water reuse, demands cooperative governance and territorial rescaling to overcome fragmentations in sectors and water policies. While the transition is challenging for local governments and crosses economic sectors and spatial scales, Inter-Municipal Cooperation IMC is gaining popularity due to its ability to contribute additional human, financial, and technological resources. However, cooperative governance arrangements require studying its benefits and impacts in its context. This study explores how IMC is being considered as a governance arrangement for the transitions towards WCE by conducting a review of the literature. The findings indicate that IMC appears as a promising government arrangement for WCE because it incorporates several significant potentials, such as facilitating the conciliation of interests between agencies, stakeholder engagement, and effective land use for water management. The literature reflects that the success of IMC for the adoption of WCE requires the simultaneous consideration of a set of governance practices, the assurance of cost efficiency and financial balance, and the assessment of social and environmental consequences. Nevertheless, these dimensions are not equally addressed by the literature. While governance and efficiency are often referred to, the assessment of IMC experiences in the context of WCE is still poorly explored, deserving further research.

The transition to the water circular economy (WCE) requires several stakeholders' awareness, articulation, and action involving complex governance concerns. As a participatory approach to identifying problems, designing solutions, and implementing strategic actions, the co-creation process should support stakeholder involvement to adjust existing institutional arrangements to foster the WCE. This article designs and applies a co-creation process to analyse the perception of key stakeholders about institutional challenges for water reuse and explore their contributions to innovate policy, planning, and governance for the implementation of new water reuse technology in Almendralejo (Spain), Lecce (Italy), Omis (Croatia), and Eilat (Israel). The findings indicate that implementing a new water loop encounters complex institutional and production-related obstacles, which different stakeholders address in varying ways. Moreover, the proposed solutions to the on-site issues identified emphasise the need for actions that foster engagement and collaboration, particularly to enhance awareness, training, and regulation. Addressing these challenges associated with adopting new water loops, even when technical, may depend on non-technical solutions regarding the institutional framework. The co-creation processes highlight the importance of focusing on institutional arrangements and stakeholder awareness while implementing new water loops to ensure and promote symbiotic territories that consider the policy, producers', and users' strategies.

This article analyses the role of inter-municipal cooperation (IMC) as a governance model in promoting water circular economy (WCE) and water reuse practices. Despite the potential benefits offered by IMC, little is known about how could contribute to fostering WCE adoption. The article develops and uses a framework to assess the role of IMC in advancing WCE strategies, addressing three key dimensions: involvement of IMC in advancing WCE, robust governance for WCE, and territorial fit and spatial concerns. It uses Portugal as a case study within the South European Union, where water scarcity and interest in IMC approaches are growing. Considering the emphasis on collaboration in legal and legislative frameworks, the results show the constrained role of inter-municipal communities in promoting the WCE through water reuse in Portugal. In addition, the limited integration of water reuse into territorial strategies highlights the lack of integration of water management and spatial planning. Moreover, the robustness of governance is hindered by a lack of funding, inadequate infrastructure, spatial barriers, a lack of experts or knowledge, and a deficiency in common goals or diversity of interests. Further research is essential to address territorial fit and spatial considerations critical to WCE adoption.