<p>Drinking water supply and water handling.</p>

Equipping water supply schemes in low-income regions with automated chlorination systems offers a compelling strategy for improving access to safe drinking water. However, previous efforts to implement passive in-line chlorinators in remote regions have struggled to establish supply chains for chlorine. We implemented a controlled pre–post interventional study at three sites with 600 households in the Sidama region in Ethiopia, where we equipped water supply systems with CLARA electro-chlorinators, which produce chlorine on site. After one year, we evaluated their effect on improving water quality at the point of consumption and improving child health. Data was collected by household interviews, anthropometric measurements of children, and water quality analysis. The intervention had a significant effect on improving drinking water quality: the percentage of samples free of contamination with E. coli at the point of water collection increased from 5.3% at baseline to 77% at endline (Z = -11.39, p < 0.001) and in household water storage containers from 3.9% at baseline to 37.9% at endline (Z = -8.524, p < 0.001). The intervention did not achieve a significant reduction in the high baseline values of stunting (32.4%) and underweight (10.7%) among children under the age of five years (prevalence ratio (PR)=1.04, 95% CI = 0.74-1.47, p = 0.813 and PR = 1.16, 95% CI = 0.69-1.98, p = 0.573). However, children living in households that reported that water had almost always been chlorinated, had a 66% lower odds ratio for stunting. This effect was marginally significant (OR=0.337, 95%CI = 0.11-1.02, p = 0.053). The prevalence of several infectious diseases fell significantly, including fever (47.2% to 24.9%), cough (47.5% to 24.4%), respiratory difficulties (13.5% to 0.8%), and diarrhoea (25.9% to 15%), but the changes were not associated with the intervention. The intervention encountered several operational challenges that constrained potential health impacts. Further studies are required to better understand the optimal operation requirements for in-line chlorination systems and assess their impact.