Every drop counts: a systematic literature review on the role of tariffs in sustainable water supply services

The sustainability of water supply represents a critical global challenge. A pivotal factor in addressing this challenge is the implementation of water tariffs, which function as an indispensable mechanism for securing the long-term availability of this invaluable resource. However, a comprehensive synthesis of the essential dimensions that underpin effective tariff design across diverse sectors remains conspicuously absent, thereby impeding the formulation of effective policy development. This study aims to bridge the gap by conducting a systematic literature review that identifies and analyzes the fundamental dimensions of water tariffs from a supply-side sustainability perspective, as articulated in contemporary literature spanning domestic, industrial, and agricultural sectors across various countries and regions. These insights have the potential to enhance the supply-side approach to water management. Employing the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guideline and a Mixed Methods Appraisal Tool (MMAT), we scrutinized 16 studies. Through thematic analysis, we discerned six key interconnected dimensions of water tariffs: affordability, efficiency, financial sustainability, regulatory framework, conservation incentives, and the sustainability of water resources, which were further delineated into 11 sub-themes. The originality of this study resides in articulating these supply-side conceptual dimensions, synthesizing disparate themes into a cohesive framework, and illuminating critical trade-offs, particularly between affordability and financial sustainability. This study serves as a vital reference for policymakers and water utilities, providing an evidence-based tool for devising multi-objective water pricing strategies that are effective in managing demand and ensuring the long-term security of the water supply.