Current source-backed cities
| City | Hardness | Category | Note |
|---|---|---|---|
| Salt Lake City, UT | 132-538 ppm / mg/L as CaCO3 | Hard to very hard by source/range | Official report table lists Total Hardness values and a SLC range; source/provider mix can vary. Use this as a broad official range rather than a single address-level value. |
| Scottsdale, AZ | 275-430 mg/L as CaCO3 | Very hard | Official area ranges; varies within the city. |
| Phoenix, AZ | 172-302 ppm / mg/L as CaCO3 | Hard to very hard | Official report range for Total Hardness. |
| Los Angeles, CA | 93-291 mg/L as CaCO3 | Moderately hard to very hard by area | LADWP lists 2022 hardness values by Water Quality Area, with averages of 8.6, 9.8, and 16.3 gpg and ranges from 5.4 to 17.0 gpg. |
| San Diego, CA | 272-284 ppm / mg/L as CaCO3 | Very hard | Official City of San Diego page says drinking water typically averages about 16 gr/gal or 276 ppm and can range from 16 to 18 gr/gal or 272 to 284 ppm depending on demand and area. |
| Las Vegas, NV | 280 ppm / mg/L as CaCO3 | Very hard | Official average value for Hardness, Total. |
| Tampa, FL | 211 mg/L as CaCO3 | Very hard | Official report says average total hardness of finished water during 2025 was 211 mg/L or 12.3 grains per gallon. |
| Houston, TX | 43.4-180 ppm / mg/L as CaCO3 | Soft to hard depending on Houston public water system | Official Houston report lists Total Hardness as CaCO3 for multiple public water systems. Houston Main System: 43.4-137 ppm, avg 110 ppm. Other systems vary, including Kingwood avg 118 ppm, Willow Chase 169-180 ppm, and District 82 66.4-154 ppm. Provider/system matching matters. |
| El Paso, TX | 175 mg/L | Hard to very hard | El Paso Water chemical analysis says hardness may be considered to average about 175 mg/L or about 10.2 grains per gallon, with source ratios constantly changing. |
| Philadelphia, PA | 100-150 ppm / mg/L | Moderately hard | Philadelphia Water Department says Philadelphia tap water is typically around 100 to 150 ppm, or about 6 to 9 grains per gallon. |
| Orlando, FL | 129 ppm / mg/L | Hard | OUC FAQ says average hardness of OUC water is 129 ppm or 7 gpg. Provider matching matters because Orlando-area service may vary. |
| Cleveland, OH | 120 mg/L as CaCO3 | Moderately hard | Cleveland Water says its water hardness is 7 grains per gallon or 120 mg/L as calcium carbonate. |
| New York City, NY | about 31; up to about 120 in blended areas mg/L as CaCO3 equivalent | Soft to moderately hard depending on supply blend | NYC DEP says citywide average hardness is about 1.8 grains/gallon as CaCO3 and can reach 7 grains/gallon where Catskill/Delaware and Croton supplies are blended. |
| Portland, OR | 7-11; groundwater about 80 ppm / mg/L as CaCO3 | Soft for Bull Run supply; moderately hard for groundwater supply | Official Portland Water Bureau report says Bull Run water, Portland’s main supply, typically has total hardness of 7 to 11 ppm, about half a grain per gallon; Portland groundwater is about 80 ppm or about 5 grains per gallon. |
| Denver, CO | soft to moderately hard | Soft to moderately hard | Denver Water says Denver’s water can be classified as soft to moderately hard, with seasonal variation and two main collection systems. |
This is not a national ranking. It only includes reviewed cities with source-backed hardness data.