Water supply infrastructure in urban Ethiopian regions often fails to meet the growing demand for clean drinking water among public schools' students and staff. A mixed-methods approach including surveys, observations, and interviews to assess the impact of expanded water supply systems on students' hygiene behaviors in urban Ethiopian schools. Students exposed to enhanced water supply networks showed an increase in handwashing frequency by 20%, with a significant shift towards regular use of soap during handwashing sessions. The study concludes that targeted water supply network expansion can effectively promote better hygiene practices among students, contributing positively to public health outcomes. Public schools should consider integrated water supply and sanitation improvements as part of their overall development plans to enhance student well-being and education quality. Hygiene Behaviour Change, Water Supply Network Expansion, Public Schools, Urban Ethiopia