From Source to Storage: Point-of-Use Drinking-Water Contamination, Household WASH, and Under-5 Morbidity in Sylhet, Bangladesh

Abstract

Child morbidity among children under five in Bangladesh is closely associated with household water, sanitation, and hygiene (WASH). However, access to an improved water source does not guarantee microbiologically safe drinking water, as faecal contamination may occur after collection during transport, handling, and storage. This study assessed the “source-to-storage” pathway during the transition from monsoon to post-monsoon in urban and rural settings in Sylhet, Bangladesh. We conducted a two-round household panel study from August to November 2025 in Sylhet Sadar, Companiganj, and Beanibazar, enrolling 300 households (100 per upazila) with at least one child aged 0-59 months. Child morbidity was recorded using established case definitions (primary outcome: diarrhoea; secondary outcomes: acute respiratory symptoms and fever) within a standardized recall interval. WASH exposures were assessed using a structured questionnaire and direct observations of sanitation functionality, handwashing readiness (availability of soap and water), and safe water storage practices. Paired drinking-water samples were collected from the primary water source and household point-of-use stored water in each round and analyzed for Escherichia coli using membrane filtration with selective media and 24-hour incubation, reporting colony-forming unit (CFU) counts per 100 mL. We delineated spatial contamination patterns, quantified recontamination between source and storage, and estimated adjusted associations between WASH indicators, E. coli levels, and morbidity using multilevel regression models accounting for clustering and repeated household measurements. These findings identify where contamination is introduced along the source-to-storage continuum and highlight which household WASH components are most strongly associated with morbidity among children under five in Sylhet.