The provision of a safe drinking water is of primary importance in society and a prerequisite for public health and economic development. In order to secure a long-term, safe and reliable supply of drinking water, and to ensure a comprehensive and integrated water planning, the development of regional water supply plans is increasingly requested in Sweden. To implement the plans, the water utilities, regional planners and politicians need to make several complex decisions and prioritize between multifaceted strategic measures. There are, however, very few decision support tools adapted for water supply management on the regional level to aid the decision makers. In order to achieve a sustainable drinking water supply, socio-economic effects need to be carefully considered. Hence, this study focuses on the development of a decision support framework for assessing socioeconomic effects of strategic decisions and alternative water supply measures by adapting costbenefit analysis (CBA) and economic valuation techniques to a long-term and regional perspective. The Gothenburg region, with its newly presented regional water supply plan, serves as a case study for which five alternative measures are evaluated: (1) centralization of water supply production; (2) centralization of water supply organization; (3) shift of the main raw water intake from the river Göta älv, a raw water source exposed to a high contamination risk, to the cleaner water of lake Vänern; (4) maximization of groundwater usage; and (5) increased number of raw water resources. The effects of each alternative are identified through literature reviews, stakeholder workshops and dialogues with experts and policy makers. To assess the non-market costs and benefits of the alternative strategies, the benefit transfer method is used for adapting estimates from national and international valuation studies to the Gothenburg region. The monetized costs and benefits are then used to set up a longrun CBA to identify the best strategy from a social welfare perspective. The net present values (NPVs) of the alternative measures are estimated for three different discount rates (constant rates of 1.4 % and 3.5 % as well as a declining discount rate) and two different time periods (ranging to 2050 and 2100). Uncertainties concerning the NPVs are analyzed by means of statistical simulation (Monte Carlo), accounting for uncertainties in input data. For the Gothenburg region, the results show the effect of the various strategies and give a direct guidance on which measures are most favorable from a cost-benefit perspective. The case study results are then used to design a general decision support framework that allows for non-market valuations and economic and ecological tradeoffs under uncertainty, a novelty on the regional scale. In conclusion, it is expected that the results of this study will provide decision makers and regional planners with a framework of tools to improve their ability to make well-informed decisions and to ensure the society a safe and reliable water supply for generations to come.