State ranking
States with the hardest water
Compare the median indexed hardness, GPG, range, and evidence count for every state and Washington, DC.
- 1South Dakota · 516 PPM
- 2North Dakota · 372 PPM
- 3Utah · 364 PPM
National data rankings
Where is US water hardest—and where is it softest?
Compare transparent rankings built from the same 14,060 published ZIP profiles used throughout Hard Water Index. Every row links back to its local evidence.
- State/DC profiles
- 51
- Qualifying cities
- 209
- Data through
- Aug 18, 2026
City ranking
Hardest-water cities in the US
Rank better-supported city medians while preserving the number and confidence of the underlying ZIP estimates.
- 1Pascagoula, MS · 2395 PPM
- 2Biloxi, MS · 1885 PPM
- 3Gulfport, MS · 1805 PPM
State ranking
States with the softest water
Start at the low end of the same national state dataset and see how much variation exists within each jurisdiction.
- 1South Carolina · 19 PPM
- 2Oregon · 29 PPM
- 3Virginia · 34 PPM
City ranking
Softest-water cities in the US
Explore the lowest qualifying city medians, with direct links to every city's evidence and local ZIP reports.
- 1White Hall, AL · 9 PPM
- 2Northport, AL · 9 PPM
- 3Rome, NY · 9 PPM
What these rankings mean
A comparison tool, not a tap-water verdict
Rankings use the median of available nearby hardness estimates. A high position means more calcium-and-magnesium hardness in the indexed evidence; it does not mean the water is unsafe. Likewise, “softest” does not mean “cleanest” or “best.” Hardness and regulated contaminants answer different questions.
State results include every published ZIP estimate and are not population weighted. City results require at least three hardness readings, at least two with High or Moderate confidence, and at least two distinct monitoring sites. This reduces the chance that one repeated estimate controls a national headline.