Safe, affordable, reliable drinking water is central to public health, strong communities, economic development, and a healthy environment. Drinking water policy and management tends to rely on regulatory monitoring and compliance, but the performance of drinking water systems is underpinned and driven by social, financial, and physical systems. When these systems are eroded or poorly functioning, drinking water systems are vulnerable to performance failures of many kinds. We develop a multidimensional approach to measuring drinking water vulnerability using composite indices and apply these methods to large (greater than 50,000 residents) cities of the Great Lakes region, an area grappling with pressing drinking water challenges. Using publicly available data, we calculate drinking water vulnerability scores for 105 cities in the region using three different index development methods. We find that there are differences in drinking water vulnerability scores between states and within metropolitan areas. We also find these vulnerability index measures are related to performance outcomes, specifically violations of the Safe Drinking Water Act. The index provides new, adaptable methods and insights into drinking water system vulnerability for scholars, decision makers, and stakeholders.
