Average water hardness in every state
Water Hardness averages 120 PPM nationally. But real averages run from 38 PPM in Arkansas to 300 PPM in Nevada. Hardness — dissolved calcium and magnesium — is what scales your kettle, spots your dishes and shortens your water heater's life. It tracks the minerals in local groundwater, so geography is destiny. Or estimate your own cost with your personal factors included.
All states ranked, softest to hardest water
State averages synthesized from USGS groundwater studies and EPA SDWIS records (Water Hardness Lab, 2026). PPM = parts per million of dissolved calcium carbonate; divide by 17.1 for grains per gallon.
| # | State | Hardness (PPM) |
|---|---|---|
| 1 | Arkansas | 38 PPM |
| 2 | Massachusetts | 50 PPM |
| 3 | Hawaii | 60 PPM |
| 4 | Maine | 60 PPM |
| 5 | New Hampshire | 60 PPM |
| 6 | Mississippi | 70 PPM |
| 7 | Oregon | 70 PPM |
| 8 | Vermont | 70 PPM |
| 9 | Washington | 70 PPM |
| 10 | Connecticut | 75 PPM |
| 11 | New York | 75 PPM |
| 12 | Rhode Island | 75 PPM |
| 13 | Montana | 95 PPM |
| 14 | Alaska | 100 PPM |
| 15 | Idaho | 100 PPM |
| 16 | Louisiana | 100 PPM |
| 17 | New Jersey | 100 PPM |
| 18 | Kentucky | 112 PPM |
| 19 | Maryland | 118 PPM |
| 20 | Illinois | 120 PPM |
| 21 | North Carolina | 120 PPM |
| 22 | Pennsylvania | 120 PPM |
| 23 | Virginia | 120 PPM |
| 24 | Georgia | 130 PPM |
| 25 | Iowa | 130 PPM |
| 26 | North Dakota | 130 PPM |
| 27 | Ohio | 130 PPM |
| 28 | South Carolina | 130 PPM |
| 29 | Tennessee | 130 PPM |
| 30 | West Virginia | 130 PPM |
| 31 | Washington D.C. | 135 PPM |
| 32 | Michigan | 140 PPM |
| 33 | Wisconsin | 140 PPM |
| 34 | Alabama | 150 PPM |
| 35 | South Dakota | 150 PPM |
| 36 | Minnesota | 175 PPM |
| 37 | Colorado | 185 PPM |
| 38 | California | 200 PPM |
| 39 | Delaware | 200 PPM |
| 40 | Florida | 200 PPM |
| 41 | Missouri | 200 PPM |
| 42 | Nebraska | 210 PPM |
| 43 | Oklahoma | 210 PPM |
| 44 | Wyoming | 210 PPM |
| 45 | Kansas | 250 PPM |
| 46 | New Mexico | 252 PPM |
| 47 | Utah | 259 PPM |
| 48 | Texas | 268 PPM |
| 49 | Arizona | 280 PPM |
| 50 | Indiana | 298 PPM |
| 51 | Nevada | 300 PPM |
State averages hide huge local swings. A certified home water test kit tells you your exact hardness and what's dissolved in your water — before you spend a dollar on treatment.
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Why the Southwest scales and New England doesn't
Hard water is geology you can taste. Rain that filters through limestone and gypsum — the bedrock under much of the Great Plains and Southwest — picks up calcium and magnesium on the way to the aquifer. Nevada, Indiana, Arizona and Texas all average above 250 PPM, deep into the USGS 'very hard' range.
New England and the Pacific Northwest sit on granite and volcanic rock that gives up almost no minerals, and heavy rainfall dilutes what little there is. Massachusetts averages around 50 PPM and most of the region tests soft to moderately hard — which is why a water softener is standard equipment in Phoenix and almost unheard of in Boston.