In Colorado, mains water is delivered by local public water systems, regulated by the Colorado Dept. of Public Health and Environment (CDPHE) under the US EPA Safe Drinking Water Act. Typical hardness: Varies; mountain snowmelt softer, plains and groundwater moderately hard to hard. For a specific ZIP, see the EWG Tap Water Database.
Sources: Colorado Dept. of Public Health and Environment (CDPHE), EWG Tap Water Database