In Iowa, mains water is delivered by local public water systems, regulated by the Iowa Dept of Natural Resources (Iowa DNR), Water Supply program under the US EPA Safe Drinking Water Act. Typical hardness: Very hard; mostly groundwater, generally above 180 mg/l. For a specific ZIP, see the EWG Tap Water Database.
Sources: Iowa Dept of Natural Resources (Iowa DNR), Water Supply program, EWG Tap Water Database