One of the main challenges undermining water supply in African cities is the rapid decay of networked infrastructures. Urban water managers, policymakers and researchers, however, have paid little attention to repair and maintenance or to their importance for the operation and renewal of urban water utilities. Using a sociotechnical framework, this paper investigates the maintenance and repair practices of utility officials from two water companies, one in Accra and one in Dar es Salaam. More specifically, through the interplay of four variables, we develop a novel analytical framework inspired by science and technology studies to explain and compare the contingent, place-based maintenance and repair practices that shape urban water supply. These four variables are materialities, discourses, institutional arrangements, and the knowledge of local experts. The two aims of this paper are to explain how the ‘everyday’ repair and maintenance practices of utility officials shape water supply, and to draw lessons for improving water supply in both cities. Our findings show that repair and maintenance practices are strongly shaped by place-based materialities and contextual knowledge in water supply, but at the same time are contingent on wider national and international relations as reflected in discourses, policies, and the supply of technical and material spare parts.