"Safe drinking water and sanitation are basic needs for human health and livelihood. Sub-Saharan Africa has low, but improving, rates of access to these services, but the infrastructure in use are often rudimentary and provide only marginal control of contaminants. The challenge of achieving universal water and sanitation service delivery in sub-Saharan Africa was investigated from a public service system perspective. A framework for defining and measuring the support systems needed to maintain infrastructure was developed and applied in six countries with the aim to foster greater alignment of implementing actors and improve practice.In the first phase of the research, interviews and field visits to promising and failed sanitation interventions in East Africa revealed the importance of both local participation and government buy-in to achieve sustainability and to be able to scale up innovations. Fragmentation of knowledge and an incomplete understanding of the problem by many actors suggested the need for a more shared understanding of how services can be provided and improved. In the second phase of the research, a conceptual and analytical framework was developed based on a review of the literature, case studies in east and west Africa, and expert consultation. The framework defined the water and sanitation system according to nine sub-systems: institutions, policy and legislation, finance, planning, regulation, monitoring, water resource management, learning and adaption, and infrastructure. These were determined to be a logical way to divide the overall system into manageable parts, based on iterative problem analyses with local and national actors. It is posited that these functionalities must be present in the national framework and understood and implemented at decentralised levels.In the third phase, the framework was applied using mixed methods participatory action-research to assess drinking water service delivery in Uganda using the case of Kabarole District. The research was carried out with a nationally registered NGO (IRC) and a learning alliance of stakeholders working in support of the Government of Uganda's objective to provide universal access to basic water by 2030, and to extend piped water to all households by 2040. Qualitative policy assessments, a review of statements from national level officials and the results from a quantitative analysis of the drinking water services in Kabarole in 2017 and 2019 were used to identify emerging trends in service delivery. Service delivery models present in Kabarole were self-supply, community management, and two different variants of a public utility model. Uganda has undergone policy reforms in recent years and is in the early stages of a transition to professionalized utility water supply systems. The research investigated the social learning of stakeholders in the learning alliance. The multi-level perspective for socio-technical systems transitions was used to analyse bottom-up and top-down innovation in Uganda. A participatory scenario development process made use of GIS maps, interviews, workshops and focus group meetings to identify the most important and uncertain factors that may influence progress toward the 2030 targets. The most likely scenario was identified, and several strategies were developed to adapt to anticipated changes while pursuing the goal of universal services. The final phase of research was a critical reflection on the WASH systems framework and assessment methodology. A public systems approach to analysis and planning was found to be useful for structuring collaborative work in a complex environment. The use of nine subsystems to define the larger system helped to reduce the complexity and aid in analysis. Participatory assessment of these subsystems was effective in helping local, national, and international actors to establish a more common understanding of the problem and to develop future visions for public service delivery"--