Safe drinking water is fundamental to public health and societal development, and groundwater supplies around half of the world’s drinking water. Yet these resources are under increasing pressure from agriculture, infrastructure development, climate change, and rising freshwater demand. This has increased the emphasis on preventive source protection rather than relying mainly on increasingly advanced treatment. Implementing such protection is far from straightforward. Effective groundwater protection must address both microbial hazards and contaminants from wider contributing areas, often creating tensions with existing land use and stakeholder interests. Although policy increasingly promotes catchment-based and risk-based approaches, their practical application remains difficult, particularly for small and medium-sized water supplies due to limited resources. At the same time, readily usable tools are often lacking, and the gap between hydrogeological science and practice continues to widen. Against this background, this thesis aims to strengthen groundwater protection for drinking water by improving how scientific methods and knowledge are applied in practice, with particular focus on Sweden. Using a Design Science Research approach, it translates selected methods into practice-oriented approaches for everyday water protection work, with emphasis on ecosystem services, risk and uncertainty, groundwater modelling, cost-benefit analysis, and environmental justice. The findings show that water protection can be strengthened by translating scientific methods into forms that are more usable in routine practice. Across the thesis, this is achieved by making uncertainty in protection zone delineation more explicit, broadening the assessment of what is at stake beyond the core drinking-water function, and creating more structured ways to connect risk, consequences, and economic reasoning in water protection planning. It also points to the importance of broader system perspectives, including environmental justice, in decision-making. The thesis further demonstrates how Design Science Research can support the development of implementable instruments for drinking-water protection, and why formalizing the design process matters for ensuring that what is developed is also useful in practice.