Delaware Water Quality Rankings

Delaware water quality overview

Delaware's drinking water quality is good overall, with a state average score of 77.1 out of 100 — 2.9 points above the national average of 74.2. The median city score is 79.4, reflecting how water quality is distributed across the state's 43 ranked cities. 84% of Delaware cities earned an A or B grade, indicating broadly strong water quality infrastructure. Only 2 cities received a failing grade. PFAS "forever chemicals" were detected in 21 of 43 cities (49%). Of those, 13 cities exceed the 2024 EPA maximum contaminant levels — a health concern requiring action. 1 city has lead levels exceeding the EPA action level of 15 ppb, typically a sign of aging lead service lines or lead solder in older plumbing. Residents in these areas should use an NSF 53-certified filter. 40 cities have recorded health-based violations with the EPA — meaning contaminant levels exceeded safe limits or required testing was missed. Use the table below to find your city's specific record.