Understanding and Improving Enforcement and Compliance with Drinking Water Standards

The quality of public drinking water poses a critical risk to public health, yet U.S. public water systems (PWSs) frequently produce water that violates drinking water standards. The causes of such violations and the effects of enforcement actions on reducing those violations remain poorly understood. We use a ten-year database of water quality violations across 2487 Connecticut (CT) water systems to test a novel analytical model that investigates drivers of water quality violations and explores the effects of enforcement actions by the state drinking water program (DWP) on the durations of violations. PWS characteristics associated with increased violations in CT include: state-ownership, groundwater dependence, and rural location. Non-transient, non-community (NTNC) systems committed fewer violations overall, but their violations lasted significantly longer than those committed by other PWS types. PWSs respond differently to formal versus informal enforcement actions, with informal enforcement actions (i.e. a letter and technical assistance) curbing duration of violations more effectively than the comparatively punitive, formal enforcement actions. Lastly, we find the U.S. Environmental Protection Agency's enforcement targeting tool (ETT) somewhat helpful for restoring PWS compliance in combination with informal enforcement action, but our analysis suggests the ETT is less effective in isolation. We demonstrate a novel analytical model that provides actionable information to state DWPs charged with enforcing drinking water standards to protect the quality of public water supplies.