50-State Water Hardness Ratings & Softener Standards
State-by-state USGS municipal water hardness ratings (grains per gallon GPG & PPM CaCO3), regional aquifer mineral profiles, and state softener efficiency & discharge regulations.
| State | Avg State Hardness | Hardness Classification | Major Metro Concentration | Softener Efficiency Standard |
|---|---|---|---|---|
| Alabama | 4.5 GPG (77 PPM) | Slightly Hard | Birmingham (5.2 GPG) | Standard Demand Initiated |
| Alaska | 6.8 GPG (116 PPM) | Moderately Hard | Anchorage (4.2 GPG) / Fairbanks (9.5 GPG) | Freeze Protected Brine Line |
| Arizona | 18.5 GPG (316 PPM) | Extremely Hard | Phoenix (16.0 GPG) / Tucson (14.2 GPG) | Demand Initiated Regeneration (DIR) |
| Arkansas | 5.2 GPG (89 PPM) | Moderately Hard | Little Rock (4.1 GPG) | Standard NSF/ANSI 44 |
| California | 16.2 GPG (277 PPM) | Extremely Hard | Los Angeles (15.5 GPG) / San Diego (18.1 GPG) | Strict NSF 44 (4,000 grains/lb salt) |
| Colorado | 12.8 GPG (219 PPM) | Very Hard | Denver (8.2 GPG) / Grand Junction (22.5 GPG) | High Efficiency DIR Required |
| Connecticut | 3.8 GPG (65 PPM) | Soft to Moderate | Hartford (3.5 GPG) | Standard NSF/ANSI 44 |
| Delaware | 6.2 GPG (106 PPM) | Moderately Hard | Wilmington (5.8 GPG) | Standard Demand Initiated |
| Florida | 17.4 GPG (298 PPM) | Extremely Hard | Tampa (18.5 GPG) / Orlando (12.4 GPG) | DIR + Iron Removal Standard |
| Georgia | 3.6 GPG (62 PPM) | Soft to Moderate | Atlanta (2.8 GPG) / Augusta (4.9 GPG) | Standard NSF/ANSI 44 |
| Hawaii | 4.8 GPG (82 PPM) | Slightly Hard | Honolulu (5.1 GPG) | Volcanic Aquifer Profile |
| Idaho | 14.1 GPG (241 PPM) | Very Hard | Boise (11.5 GPG) / Idaho Falls (18.0 GPG) | Demand Initiated Standard |
| Illinois | 15.8 GPG (270 PPM) | Extremely Hard | Chicago (8.5 GPG) / Rockford (22.0 GPG) | High Efficiency DIR Meter |
| Indiana | 19.6 GPG (335 PPM) | Extremely Hard | Indianapolis (18.0 GPG) / Fort Wayne (21.5 GPG) | High Capacity Cation Resin |
| Iowa | 18.2 GPG (311 PPM) | Extremely Hard | Des Moines (16.5 GPG) / Cedar Rapids (19.0 GPG) | Demand Regenerated DIR |
| Kansas | 17.5 GPG (299 PPM) | Extremely Hard | Wichita (14.8 GPG) / Overland Park (12.2 GPG) | DIR Softener Efficiency |
| Kentucky | 11.4 GPG (195 PPM) | Hard | Louisville (10.5 GPG) / Lexington (13.2 GPG) | Standard NSF/ANSI 44 |
| Louisiana | 4.9 GPG (84 PPM) | Slightly Hard | New Orleans (6.2 GPG) / Baton Rouge (3.5 GPG) | Standard Metered Valve |
| Maine | 2.9 GPG (50 PPM) | Soft | Portland (2.4 GPG) | Low Hardness Profile |
| Maryland | 5.8 GPG (99 PPM) | Moderately Hard | Baltimore (4.5 GPG) / Frederick (9.2 GPG) | Standard NSF/ANSI 44 |
| Massachusetts | 3.1 GPG (53 PPM) | Soft | Boston (2.5 GPG) / Worcester (3.8 GPG) | Standard NSF/ANSI 44 |
| Michigan | 13.5 GPG (231 PPM) | Very Hard | Detroit (6.2 GPG) / Grand Rapids (16.8 GPG) | DIR Meter Standard |
| Minnesota | 16.8 GPG (287 PPM) | Extremely Hard | Minneapolis (12.0 GPG) / St. Cloud (21.5 GPG) | State Salt Reduction Rebate Standard |
| Mississippi | 4.2 GPG (72 PPM) | Slightly Hard | Jackson (3.8 GPG) | Standard NSF/ANSI 44 |
| Missouri | 12.2 GPG (209 PPM) | Hard | St. Louis (10.5 GPG) / Kansas City (13.8 GPG) | Demand Initiated Standard |
| Montana | 13.8 GPG (236 PPM) | Very Hard | Billings (12.4 GPG) / Bozeman (14.5 GPG) | Demand Initiated Standard |
| Nebraska | 16.9 GPG (289 PPM) | Extremely Hard | Omaha (13.5 GPG) / Lincoln (15.2 GPG) | DIR Softener Efficiency |
| Nevada | 19.8 GPG (339 PPM) | Extremely Hard | Las Vegas (18.2 GPG) / Reno (6.5 GPG) | Strict DIR Efficiency Standards |
| New Hampshire | 3.2 GPG (55 PPM) | Soft | Manchester (2.8 GPG) | Standard NSF/ANSI 44 |
| New Jersey | 6.5 GPG (111 PPM) | Moderately Hard | Newark (5.2 GPG) / Trenton (7.8 GPG) | Standard Demand Initiated |
| New Mexico | 21.4 GPG (366 PPM) | Extremely Hard | Albuquerque (14.2 GPG) / Roswell (28.5 GPG) | High Efficiency DIR Mandate |
| New York | 6.8 GPG (116 PPM) | Moderately Hard | NYC (1.8 GPG) / Buffalo (12.5 GPG) | Regional Aquifer Variance |
| North Carolina | 3.4 GPG (58 PPM) | Soft | Charlotte (2.6 GPG) / Raleigh (3.1 GPG) | Standard NSF/ANSI 44 |
| North Dakota | 17.1 GPG (292 PPM) | Extremely Hard | Fargo (15.8 GPG) / Bismarck (18.2 GPG) | High Capacity Softeners |
| Ohio | 15.4 GPG (263 PPM) | Extremely Hard | Columbus (14.0 GPG) / Cincinnati (11.5 GPG) | Demand Initiated Standard |
| Oklahoma | 14.8 GPG (253 PPM) | Very Hard | Oklahoma City (13.5 GPG) / Tulsa (9.5 GPG) | Standard Demand Initiated |
| Oregon | 3.8 GPG (65 PPM) | Soft | Portland (1.2 GPG) / Bend (7.5 GPG) | Standard NSF/ANSI 44 |
| Pennsylvania | 8.9 GPG (152 PPM) | Moderately Hard | Philadelphia (6.8 GPG) / Pittsburgh (9.2 GPG) | Standard Demand Initiated |
| Rhode Island | 2.8 GPG (48 PPM) | Soft | Providence (2.2 GPG) | Standard NSF/ANSI 44 |
| South Carolina | 3.2 GPG (55 PPM) | Soft | Charleston (4.1 GPG) / Columbia (2.5 GPG) | Standard NSF/ANSI 44 |
| South Dakota | 18.9 GPG (323 PPM) | Extremely Hard | Sioux Falls (16.2 GPG) / Rapid City (22.5 GPG) | DIR Softener Efficiency |
| Tennessee | 6.8 GPG (116 PPM) | Moderately Hard | Nashville (6.5 GPG) / Memphis (4.2 GPG) | Standard NSF/ANSI 44 |
| Texas | 18.1 GPG (310 PPM) | Extremely Hard | San Antonio (20.5 GPG) / Austin (12.8 GPG) | DIR Metering Mandate |
| Utah | 20.5 GPG (351 PPM) | Extremely Hard | Salt Lake City (17.5 GPG) / St. George (24.0 GPG) | High Efficiency DIR Standard |
| Vermont | 5.1 GPG (87 PPM) | Moderately Hard | Burlington (4.8 GPG) | Standard NSF/ANSI 44 |
| Virginia | 5.4 GPG (92 PPM) | Moderately Hard | Richmond (4.2 GPG) / Virginia Beach (6.1 GPG) | Standard NSF/ANSI 44 |
| Washington | 4.1 GPG (70 PPM) | Soft | Seattle (1.5 GPG) / Spokane (9.8 GPG) | Standard NSF/ANSI 44 |
| West Virginia | 7.5 GPG (128 PPM) | Moderately Hard | Charleston (6.8 GPG) | Standard Demand Initiated |
| Wisconsin | 16.4 GPG (280 PPM) | Extremely Hard | Milwaukee (8.5 GPG) / Madison (19.8 GPG) | Strict DIR Efficiency Mandate |
| Wyoming | 15.2 GPG (260 PPM) | Extremely Hard | Cheyenne (11.8 GPG) / Casper (16.5 GPG) | Demand Initiated Standard |