Beyond Transplanted Thresholds: Country‐Calibrated Fuzzy Water Poverty Indices for SDG ‐6 in MENA

ABSTRACT Cross‐country water poverty assessments in the Middle East and North Africa (MENA) often rely on transplanted benchmarks—most notably a 5% water‐expenditure share and a 30‐min access rule. Such uniform cut‐offs can overlook differences in tariff structures, consumption patterns, settlement conditions, and service reliability, thereby weakening the policy relevance of SDG‐6 diagnostics. This paper develops a country‐calibrated fuzzy water poverty index for Tunisia, Egypt, Morocco, Jordan, and Saudi Arabia. Membership functions are estimated from household microdata using country‐specific empirical distributions of affordability (water expenditure shares), access burdens (including queuing time), and reliability constraints. Where available, calibration is anchored to reported hardship—such as bill‐payment difficulty and reliance on coping strategies—and implemented within a hierarchical framework that improves robustness while preserving cross‐country comparability through percentile alignment and latent‐scale normalisation. The results reveal substantial heterogeneity in hardship onset: for example, the affordability gradient that accelerates around 5% in Tunisia corresponds to roughly 6%–7% in Egypt, while time‐based access rules are particularly prone to misclassification where queuing dominates effective access costs. Compared with conventional binary and pooled‐fuzzy baselines, the calibrated indices exhibit stronger predictive validity for hardship outcomes and yield policy‐actionable vulnerability profiles that support tariff reform, infrastructure prioritisation, and equity‐oriented water governance under SDG‐6.