Source-backed city hardness values
| City | Hardness | GPG | Category | Source |
|---|---|---|---|---|
| Salt Lake City, UT | 132-538 ppm / mg/L as CaCO3 | 7.7-31.5 | Hard to very hard by source/range | Salt Lake City Department of Public Utilities 2024 Drinking Water Quality Report |
| Scottsdale, AZ | 275-430 mg/L as CaCO3 | 16-25 | Very hard | City of Scottsdale Hard Water Facts |
| Phoenix, AZ | 172-302 ppm / mg/L as CaCO3 | 10-17.6 | Hard to very hard | City of Phoenix 2025 Water Quality Report |
| Los Angeles, CA | 93-291 mg/L as CaCO3 | 5.4-17.0 | Moderately hard to very hard by area | LADWP Water Quality FAQs |
| San Diego, CA | 272-284 ppm / mg/L as CaCO3 | 16-18 | Very hard | City of San Diego Water Quality page |
| Las Vegas, NV | 280 ppm / mg/L as CaCO3 | 16 | Very hard | Las Vegas Valley Water District 2026 Water Quality Summary |
| Tampa, FL | 211 mg/L as CaCO3 | 12.3 | Very hard | City of Tampa 2025 Water Quality Report |
| Houston, TX | 43.4-180 ppm / mg/L as CaCO3 | 2.5-10.5 | Soft to hard depending on Houston public water system | Houston Water Quality Report 2024 |
| El Paso, TX | 175 mg/L | 10.2 | Hard to very hard | El Paso Water chemical analysis |
| Philadelphia, PA | 100-150 ppm / mg/L | 6-9 | Moderately hard | Philadelphia Water Department Drinking Water FAQ |
| Orlando, FL | 129 ppm / mg/L | 7 | Hard | OUC Water Services page |
| Cleveland, OH | 120 mg/L as CaCO3 | 7 | Moderately hard | Cleveland Water hard-water explainer |
| New York City, NY | about 31; up to about 120 in blended areas mg/L as CaCO3 equivalent | about 1.8; up to 7 | Soft to moderately hard depending on supply blend | NYC DEP Drinking Water FAQs |
| Portland, OR | 7-11; groundwater about 80 ppm / mg/L as CaCO3 | about 0.5; groundwater about 5 | Soft for Bull Run supply; moderately hard for groundwater supply | Portland Water Bureau 2025 Drinking Water Quality Report |
| Denver, CO | soft to moderately hard | Soft to moderately hard | Denver Water hardness page |
Important limitation
Hardness can vary by provider, source water, treatment plant, season, and address. Use this table as a planning starting point and confirm with a current utility source or direct hardness test before sizing equipment.
Browse state hardness guides
Arizona
Arizona guide for Phoenix, Scottsdale, Mesa, Tucson, and desert hard-water context.
California
California guide for Los Angeles, San Diego, San Jose, Bakersfield, Riverside, and provider-boundary issues.
Colorado
Colorado guide for Denver and Colorado Springs source and seasonal variation.
Florida
Florida guide for Tampa, Orlando, Miami, Jacksonville, Gulf Coast cities, and city/county utility differences.
Georgia
Georgia guide for Atlanta and local provider/source context.
Idaho
Idaho guide for Boise-area provider matching and local report context.
Illinois
Illinois guide for Chicago and Lake Michigan source context.
Indiana
Indiana guide for Indianapolis and Citizens Energy Group context.
Maryland
Maryland guide for Baltimore DPW and local testing considerations.
Massachusetts
Massachusetts guide for Boston, MWRA supply, and local building context.
Michigan
Michigan guide for Detroit, Grand Rapids, and local utility differences.
Minnesota
Minnesota guide for Minneapolis and local treatment context.
Nevada
Nevada guide for Las Vegas, Reno, very hard water, and TMWA/provider matching.
New Mexico
New Mexico guide for Albuquerque and ABCWUA reporting.
New York
New York guide for NYC, Long Island, watershed water, and district/provider differences.
North Carolina
North Carolina guide for Charlotte, Raleigh, Durham, and city utility context.
Ohio
Ohio guide for Cleveland and system-specific hardness context.
Oregon
Oregon guide for Portland, Eugene, Bull Run supply, and groundwater differences.
Pennsylvania
Pennsylvania guide for Philadelphia, Pittsburgh, and local source/provider context.
Tennessee
Tennessee guide for Memphis, Nashville, aquifer, and Metro Water Services context.
Texas
Texas guide for Houston, Austin, Dallas, San Antonio, El Paso, and large utility variation.
Utah
Utah guide for Salt Lake City and source-dependent hard-water ranges.
Washington DC
Washington, DC guide for DC Water, Washington Aqueduct, and building plumbing context.
Washington
Washington guide for Seattle, Tacoma, watershed context, and provider details.
Wisconsin
Wisconsin guide for Milwaukee and Lake Michigan source context.