Consolidation without a common baseline: a review of drinking water system consolidation policies across OECD countries

Local water system consolidation is promoted to address challenges associated with small and underperforming systems, yet little research compares how countries define, pursue or measure consolidation. We develop a comparative framework organized around system definitions and regulatory baselines, policy intent and consolidation mechanisms, and observed consolidation and its measurement. We apply the framework across all 38 Organisation for Economic Co-operation and Development (OECD) countries using peer-reviewed literature, policy and regulatory documents, quantitative data and expert interviews. We find variation in system definitions, consolidation policies and measurement practices. These differences limit cross-national comparability and complicate efforts to assess consolidation and its effects on water service outcomes.