Reuse of Drinking Water in the Built Environment: Types of Conflict, Legitimacy and Governance

Potable water reuse (direct and indirect; DPR/IPR) is increasingly proposed to strengthen urban water security under climate variability, water scarcity, and rising demand. Although technological barriers have decreased considerably, many projects continue to face intense social and political conflicts. This article examines the contextual factors that explain why some technically viable reuse initiatives succeed while others fail, by developing a conceptual framework to analyse conflicts associated with DPR/IPR. The study proposes three complementary typological matrices: Justification × Acceptance (J×A), Justification × Urgency (J×U) and Demands × Repertoires (D×R). These matrices integrate the structural conditions of the projects with the strategic dynamics of the actors involved. The framework is illustrated by an empirical corpus of 25 global DPR/IPR cases, compiled through a realistic synthesis of academic literature, technical reports and contextual sources. The analysis shows that project trajectories do not depend solely on technological maturity or water scarcity. They are shaped by the interaction between technical justification, social acceptance, perceived urgency and, especially, the strategy and agency capacity of actors to mobilise demands, narratives and repertoires of action. Consequently, the advancement, transformation or blocking of potable reuse projects is mainly explained by how these strategies shape the legitimacy of water risk governance.