There is a growing effort to provide drinking water that has the trust of consumers, but the processes underlying the perception of drinking water quality and risks are still not fully understood. This paper intends to explore the factors involved in public perception of the quality and risks of drinking water. This purpose was addressed with a cross-national mixed-method approach, based on quantitative (survey) and qualitative (focus groups) data collected in the UK and Portugal. The data were analysed using several methods, including structural equation models and generalised linear models. Results suggest that perceptions of water quality and risk result from a complex interaction of diverse factors. The estimation of water quality is mostly influenced by satisfaction with organoleptic properties (especially flavour), risk perception, contextual cues, and perceptions of chemicals (lead, chlorine, and hardness). Risk perception is influenced by organoleptics, perceived water chemicals, external information, past health problems, and trust in water suppliers, among other factors. The use of tap and bottled water to drink was relatively well explained by regression analysis. Several cross-national differences were found and the implications are discussed. Suggestions for future research are provided.