Evaluating Sustainable Development Goal 6 Performance in the European Union: A Multi‐Criteria Assessment of Water Use Efficiency and Water Stress

ABSTRACT This study assesses SDG 6.4 performance across 27 EU member states using six sector‐specific FAOSTAT indicators for 2021–2023. Three‐year means were equally weighted and ranked using VIKOR ( v = 0.75). Missing agricultural water‐use efficiency values for Ireland and Luxembourg were replaced with country‐specific historical means. Luxembourg ranked first ( Q i = 0.147), followed by Sweden (0.405), Slovakia (0.414), the Netherlands (0.458), and Denmark (0.502); Spain ranked last (1.000). Both acceptability conditions were satisfied. Zero substitution changed only the positions of Ireland and Finland. At v = 0.50, Slovakia and Luxembourg formed the compromise solution set; at v = 0.25, Slovakia satisfied both conditions. Rankings were more sensitive to the compromise parameter than to the tested missing‐value assumption. Historical substitutions introduce temporal uncertainty, and the results should be interpreted as comparative indicator performance rather than direct measures of water governance quality.