Evaluating violations of drinking water regulations

This article evaluates US Environmental Protection Agency (USEPA) data for violations by community water systems (CWSs), including size, source water, and violation type. Findings include: (1) 55% of CWSs had at least one violation of a Safe Drinking Water Act (SDWA) regulation; (2) there is no difference in the presence of violations in groundwater and surface water systems; (3) fewer than 20% of CWSs with violations exceeded a maximum contaminant level (MCL) or violated a treatment technique (TT); (4) smaller systems are no more likely than larger systems, except very large systems, to violate health-related requirements; and (5) smaller CWSs appear more likely than larger systems to violate monitoring, reporting, and notification requirements. Four contaminants-total coliform, Stage 1 disinfection by-products (DBPs), arsenic, and lead and copper-that were the subject of health-related violations by more than 1% of CWSs are also evaluated.