Scholars and practitioners advocate evidence-based decision-making (EBDM) because facts lead to beneficial outcomes. At the same time, EBDM to reduce risks in water quality is under-studied. We examine types of decision-making by water utilities and government agencies, and the nature and origin of evidence available to them in their work on delivering safe drinking water to households. Using qualitative content analysis, we comparatively analyze water utilities and government agencies in Malawi, Ecuador, and Brazil. The results show that the water utilities perform combinations of decision-making types on water quality such as implementation, intelligence-gathering, and evaluation and choice, while government agencies perform more intelligence gathering. Sources and types of information are mainly water consumers, guidelines for water quality standards, and self-monitoring from water utilities. The analysis is useful in establishing a foundation for developing evidence-based management within water supply services, and potentially other water resources management activities.