In-line chlorination for drinking water in rural Odisha, India: a randomized controlled implementation trial

In-line chlorination automatically treats drinking water in piped water systems or at points-of-collection, substantially reducing morbidity and mortality while averting the burden of water treatment on individuals. Approximately 2.3 billion people globally use fecally contaminated drinking water infrastructure that is potentially compatible with in-line chlorination. In India, the Ministry of Jal Shaktis Jal Jeevan Mission has increased access to piped drinking water among rural households, however, water is often supplied intermittently without treatment. The aims of this study were to 1) test installation and operational procedures for in-line chlorination in rural drinking water systems, 2) evaluate acceptability and adoption of chlorinated water, and 3) assess reductions in drinking water fecal contamination, including with antibiotic resistant bacteria. We conducted a randomized controlled implementation trial of in-line chlorination in 20 villages in Rayagada district, Odisha, India over a 1-year period. Data collection included a baseline and post-intervention census (N=914) and surveys with a random subset of households over six timepoints (N=1,041) to assess water quality. We discuss operational challenges, including maintaining consistent chlorine dosing and addressing taste and odor preferences. In the treatment group, we detected free chlorine residual in 51% of tap water samples; this prevalence rose to 80% after increasing the target dose. Despite taste complaints in treatment communities, participants continued using piped water as their primary drinking water source. Individuals in treatment communities reported reduced time spent manually treating their drinking water, a responsibility borne by women in 92% of households. Treatment reduced E. coli prevalence by 70% in household tap water and by 47% in stored water, as well as reduced the presence of antibiotic resistant E. coli. In-line chlorination can lead to better quality water, lower the time burden of water treatment, and increase user adoption of chlorinated drinking water, but achieving this requires dedicated implementation and monitoring.