Beyond universal access: mapping regional inequalities and spatial coldspots in India’s WaSH sector toward SDG 6

National averages can conceal significant sectoral disparities and long-standing subnational injustices, despite the fact that India’s flagship programs had significantly improved access to water and sanitation. This report provided a thorough, data-driven evaluation of the water, sanitation, and hygiene (WaSH) in all 37 Indian states and union territories (UTs) using 25 indicators. Pearson’s correlation, network analysis, hierarchical clustering, principal component analysis, data envelopment analysis, Theil inequality, and spatial additive decomposition were all included in this multi-methodological framework. Results showed that, in contrast to the varied topographical constraints of larger states, lower administrative scales enable more consistent service delivery. A crucial ‘construction-outcome paradox’ was found, showing improvements in physical infrastructure do not always transfer into improvements in public health, especially when it comes to childhood stunting and nutritional outcomes. Functional school restrooms for girls were identified by network analysis as a key ‘bridge node’ and strategic force multiplier for integrated sub-national development. High-GDP states frequently showed a significant ‘hygiene-economy gap’ in behavioral indicators and waste processing, while spatial breakdown reveals spatially infectious ‘coldspots’ in the Northeast. Based on our empirical findings, we provide context-specific policy recommendations related to water, sanitation, and hygiene, to ensure functional sustainability and accomplish Sustainable Development Goal 6 by 2030.