Hidden Failures: Health Risks and Trust in Settings of Unreliable Water Service

The management of intermittent water supplies (IWS) has received research attention for over 25 years. Its negative impacts on infrastructure, water management, and public health have been identified globally. However, the increasing prevalence of IWS and the challenges in transitioning to continuous water supply raise the question of whether siloed engineering solutions fully address the complexity of service discontinuity. Little attention has been given to how IWS drives end-users to store water, shapes household water management, and influences user trust—factors that may impact population health. This oversight paints a limited picture of the consequences of IWS, as it fails to consider end-users as active participants in IWS schemes, assuming they consume water as soon as it leaves the tap. In this thesis, I address these gaps by applying a multidimensional approach to water quality and health risk characterization in IWS systems, focusing on household water management strategies and end-user trust. In the first stage of research, I evaluated microbial health risks associated with consuming contaminated water in an IWS by conducting a water quality and end-user survey campaign, along with a Quantitative Microbial Risk Assessment (QMRA) of tap and stored drinking water in Cajibío, Colombia. Based on these findings, I formulated and implemented a participatory risk modelling approach that involved end-user knowledge in the development of community-informed microbial risk assessments (inf-QMRA). Finally, I investigated current strategies for building trust-based relationships between end-users and service providers. The results highlight three hidden failures in drinking water risk assessments: neglect of the end-user’s role, isolation of the risk assessment process from those exposed, and distrust between service providers and end-users. To conclude, I reflect how these failures may evolve in the context of climate change, water scarcities, and competing water uses. Finally, I suggest implementable strategies for safer water storage and propose a water quality communication framework to facilitate dialogues between end-users and water service providers.