Spatial assessment of Water, Sanitation, and Hygiene (WASH) infrastructure, groundwater quality, and their association with childhood diarrhoeal risk in India

BACKGROUND: Diarrhoea has become a leading cause of mortality among young children, especially in low- and middle-income countries. Despite significant developments in Water, Sanitation, and Hygiene (WASH) in recent years, regional disparities persist. This research aims to examine the spatial heterogeneities in the prevalence of diarrhoea across districts in India and explore how unimproved WASH facilities and untreated groundwater quality contribute to diarrhoeal diseases using data from the fifth round of the National Family Health Survey [1] and Central Ground Water Board (CGWB), Government of India, for the corresponding period. METHODS: The spatial clustering of diarrhoea was examined using univariate local indicator of spatial association (LISA) and bivariate LISA maps, and Moran's I statistics. Finally, Ordinary Least Squares Regression (OLS), Spatial Lag Model (SLM), and Spatial Error Model (SEM) were fitted to examine the associations between WASH, groundwater quality, and the risk of diarrhoea. Indeed, spatial regression models revealed significant spatial autocorrelation (SEM λ = 0.560, p < 0.001; SLM ρ = 0.522) and better-fitting models than OLS. The lack of improved sanitation and hygiene was significantly associated with an increased risk of diarrhoea, even after adjusting for spatial autocorrelation. RESULTS: The study revealed that more than 75% of children under five years in India reside in households with unimproved WASH facilities. About 7.3% of children under five suffered diarrhoea, with relatively higher prevalence among households lacking improved sanitation and hygiene facilities. Furthermore, about 25% of Indian districts had groundwater quality unsuitable for drinking (highlighting spatial variation across districts/states). LISA maps and Moran's I (0.274, p < 0.01) identified spatial clustering of diarrhoea, with hotspots predominantly located in the eastern and central parts of India. CONCLUSIONS: The findings from our study confirmed that the spatial pattern of diarrhoea was associated with groundwater contamination, particularly in areas with elevated nitrate and total dissolved solids (TDS). Therefore, policymakers are encouraged to make concerted efforts to improve access to quality WASH facilities and enhance groundwater quality to reduce the burden of diarrhoea among children, particularly in India's high-cluster districts.