Associations between sanitary inspection risk factors and <i>E. coli</i> contamination in household groundwater sources

ABSTRACT Over 760 million people across South Asia, Southeast Asia, and the Pacific rely on self-supplied drinking water, which is frequently contaminated with faecal indicator bacteria such as Escherichia coli. Sanitary inspections (SIs) are widely used to identify contamination risks. The relationship between SI and water quality is complex, with mixed findings from previous work. This study seeks to build on the evidence by examining associations between sanitary risk factors and the presence of E. coli in household groundwater sources in Indonesia, using data from a nationally representative drinking water quality survey that sampled 6,549 households (4,104 dug wells, 2,445 boreholes). Multiple logistic regression was used to assess associations between individual SI risk factors, overall sanitary scores, and E. coli detection in boreholes and dug wells across urban and rural settings. Significant associations (p &amp;lt; 0.05) were found between E. coli and sanitary scores and risk factors, including poor plastering of rims in urban dug wells, and other sources of pollution within 10 m for rural boreholes. No significant associations were observed for urban boreholes. These findings suggest that SI tools may require adaptation for urban groundwater contexts and that hydrogeological data should be used to determine context-specific separation distances.