Data · 18 metros · verified Oct 2026
City water hardness index
Every reading below comes from a utility's own water quality report. No estimates, no third-party databases. Find your city, check the source, then carry the number into the sizing calculator.
How hardness is classified
Hardness in grains per gallon: under 1 is soft, 1–3.5 slightly hard, 3.5–7 moderately hard, 7–10.5 hard, and above 10.5 very hard. Every city in the index below is banded on this scale; a utility that publishes a range is banded on the midpoint.
The index
Default order is hardest first; the table re-sorts by city, utility, hardness, source year, or verification date. Where a utility publishes a range, the row shows the range and classification uses its midpoint.
| Class | |||||
|---|---|---|---|---|---|
| Indianapolis, IN | Citizens Energy Group | 8.7–26.9 gpg148–460 mg/L · reported range | Very hard | 2025 CCR ↗ | |
| San Antonio, TX | San Antonio Water System | 15–20 gpg256.5–342 mg/L · reported range | Very hard | 2025 utility ↗ | |
| Las Vegas, NV | Las Vegas Valley Water District | 16.4 gpg280 mg/L | Very hard | 2025 CCR ↗ | |
| San Diego, CA | City of San Diego Public Utilities Department | 11.7–16.7 gpg200–285 mg/L · reported range | Very hard | 2025 CCR ↗ | |
| Phoenix, AZ | City of Phoenix Water Services Department | 10.1–17.7 gpg172–302 mg/L · reported range | Very hard | 2025 CCR ↗ | |
| Tampa, FL | Tampa Water Department | 12.3 gpg211 mg/L | Very hard | 2025 CCR ↗ | |
| Los Angeles, CA | Los Angeles Department of Water and Power (LADWP) | 5.4–17 gpg93–291 mg/L · reported range | Very hard | 2025 utility ↗ | |
| Salt Lake City, UT | Salt Lake City Department of Public Utilities | 8–12.4 gpg136–212 mg/L · reported range | Hard | 2025 CCR ↗ | |
| Omaha, NE | Metropolitan Utilities District | 8–13 gpg136.8–222.3 mg/L · reported range | Hard | 2025 CCR ↗ | |
| Chicago, IL | Chicago Department of Water Management | 7.6–8.8 gpg130–150 mg/L · reported range | Hard | 2018 utility ↗ | |
| Houston, TX | Houston Public Works (Houston Water) | 2.5–13.4 gpg43.5–229 mg/L · reported range | Hard | 2025 CCR ↗ | |
| Fort Worth, TX | Fort Worth Water (City of Fort Worth) | 6.3–8.8 gpg108–150 mg/L · reported range | Hard | 2025 CCR ↗ | |
| Orlando, FL | Orlando Utilities Commission (OUC) | 7.5 gpg129 mg/L | Hard | 2025 utility ↗ | |
| Columbus, OH | Columbus Water & Power | 5–7.7 gpg85–132 mg/L · reported range | Moderately hard | 2025 CCR ↗ | |
| Denver, CO | Denver Water | 3.2–7.3 gpg55–124 mg/L · reported range | Moderately hard | 2025 CCR ↗ | |
| Kansas City, MO | KC Water | 5.8 gpg100 mg/L | Moderately hard | 2025 utility ↗ | |
| Minneapolis, MN | Minneapolis Water Treatment & Distribution (City of Minneapolis) | 4.7–6.6 gpg80–113 mg/L · reported range | Moderately hard | 2025 utility ↗ | |
| Austin, TX | Austin Water | 4.1–7.4 gpg70–126 mg/L · reported range | Moderately hard | 2025 CCR ↗ |
gpg = grains per gallon = mg/L as CaCO₃ ÷ 17.1. A utility that publishes an average plus a maximum shows both. The Verified column is the date we last read the linked document. Sourcing rules: how we verify.
How we verify
Each row is read from the utility's most recent Consumer Confidence Report, the annual water quality document federal law requires every utility to publish. When a report publishes no hardness figure, the utility's own water quality page is used instead. We record the exact quoted line and the document it came from, and we re-check every row on a schedule.
Full rules live in our methodology. City not listed? Enter your hardness by hand in the sizing calculator, or start with the free water test guide.