Free ZIP code lookup
Water Hardness by ZIP Code
Search a ZIP code or city to see local water hardness in PPM and grains per gallon, matched water systems, and source confidence for the reading.
Featured ZIP Code Reports
A national sample showing soft, moderate, hard, and very hard local readings with source labels.
How ZIP Code Hardness Is Calculated
A ZIP code can be served by one or more public water systems. WaterHardness.org matches ZIP codes to systems, normalizes hardness values to PPM as calcium carbonate, converts to GPG, and labels the source behind each local value.
Direct treated-water reports are preferred where available. USGS monitoring, county medians, and state medians are used only when better local evidence is unavailable.
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ZIP Lookup FAQ
Can hardness vary within a ZIP code?
Yes. A ZIP can include multiple utility zones, private wells, or blended sources. Use the matched water systems and source label to judge how local the reading is.
Is water hardness a safety score?
No. Hardness measures calcium and magnesium mineral content. For contaminant compliance, review your utility Consumer Confidence Report or certified lab results.
What units are shown?
Values are shown as PPM or mg/L as calcium carbonate and can be converted to grains per gallon using 17.1 PPM per 1 GPG.
Should I test my tap water?
Test before sizing treatment equipment. Local plumbing, private wells, seasonal source changes, and utility blending can change what reaches your tap.