Abstract

Diarrhoeal disease remains a leading cause of illness and death among children under five in low- and middle-income 
regions, including East Africa. Municipal (piped) water supply, when safely managed, reliably available, and 
microbiologically safe at the point of use, is a central public-health intervention that can reduce exposure to enteric 
pathogens and lower diarrhoeal incidence. This review synthesizes evidence on how municipal water systems affect 
diarrhea outcomes in East Africa, examines the mechanisms by which piped water reduces disease risk, and discusses 
barriers that limit protective effects (intermittency, contamination, inequitable access, household storage practices, 
and governance). We summarize findings from global systematic reviews and regional primary studies showing 
sizeable reductions in diarrhoea associated with improved and safely managed water services, but also emphasize 
mixed results when systems are intermittent or water quality is poor. Climate variability, urbanization, and aging 
infrastructure further challenge the delivery of safe municipal water in East African cities and towns. We highlight 
successful programmatic elements, continuous piped supply, disinfection at source, household connection coverage, 
leak control, and community engagement, and propose a set of policy, investment, and research priorities tailored 
to the East African context. Strengthening municipal water systems is necessary but not sufficient for sustained 
diarrhoea reduction; coordinated action across water, sanitation, hygiene (WASH), health, and urban planning 
sectors is required. Finally, we identify critical research gaps, including robust impact evaluations of municipal 
upgrades on health outcomes, cost-effectiveness analyses in East African settings, and operational studies addressing 
intermittency and equity.