Colorado tap water by county

Hardness, PFAS sampling, lead and violations for the largest water systems in 8 Colorado counties. In 6 of them, at least one large system detected PFAS in EPA testing (a detection isn't a violation).

CountyLargest systemHardnessPFAS detected
El Paso CountyColorado Springs Utilities9.1 gpg (low)4 of 6 systems
Denver CountyDenver Water Board6.1 gpg (high)0 of 2 systems
Arapahoe CountyAurora City of6.6 gpg (high)4 of 4 systems
Jefferson CountyArvada City of6.4 gpg (low)1 of 3 systems
Adams CountyThornton City of13.3 gpg (low)3 of 5 systems
Douglas CountyCastle Rock Town of7.0 gpg (low)4 of 6 systems
Larimer CountyFt Collins City of1.1 gpg (low)1 of 6 systems
Weld CountyGreeley City of32.1 gpg (low)0 of 6 systems

Public-record figures, not a test of your tap. Not 100% accurate or guaranteed. Confirm with a water test, your utility or a qualified pro before you buy or act.

Hardness confidence: high = utility report; low = county estimate of untreated local water. Don't see your county? Use the water quality lookup.