Colorado Water Quality Rankings

Colorado water quality overview

Colorado's drinking water quality is fair overall, with a state average score of 66.1 out of 100 — 8.1 points below the national average of 74.2. The median city score is 69.5, reflecting how water quality is distributed across the state's 246 ranked cities. 38% of cities scored a D or F, pointing to significant water quality challenges across much of the state. 119 cities did earn an A or B grade, showing that strong systems do exist. PFAS "forever chemicals" were detected in 67 of 246 cities (27%). Of those, 10 cities exceed the 2024 EPA maximum contaminant levels — a health concern requiring action. 3 cities have 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. 206 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.