Water hardness in Indiana
Indiana has a median ambient water hardness of 280 mg/L, which is 16.4 grains per gallon and classes as very hard. That is the middle of 31,856 samples across 92 counties.
This is ambient water, not tap water. These figures come from samples taken from wells, streams and springs by USGS, EPA and state agencies. Municipal utilities treat, blend and sometimes soften water before it reaches a tap, so a city supply can be considerably softer than the ground beneath it. Treat this as a good guide for a private well and an approximate one for city water. Your utility's annual water quality report gives the real number for a municipal tap, and a test strip gives it for yours.
Every monitored county in Indiana
Ranked hardest first. The middle 50% column shows how much the samples within a county vary, which matters more than the median where a county spans two geologies.
| County | mg/L | gpg | Class | Middle 50% | Samples |
|---|---|---|---|---|---|
| Warrick County | 450 | 26.3 | Very hard | 242 to 959 | 109 |
| Henry County | 374 | 21.8 | Very hard | 338 to 406 | 156 |
| Jay County | 374 | 21.8 | Very hard | 300 to 439 | 321 |
| Blackford County | 371 | 21.7 | Very hard | 290 to 430 | 89 |
| Whitley County | 358 | 20.9 | Very hard | 327 to 392 | 145 |
| Madison County | 342 | 20 | Very hard | 305 to 367 | 372 |
| Clinton County | 341 | 19.9 | Very hard | 309 to 365 | 287 |
| Marshall County | 340 | 19.9 | Very hard | 300 to 350 | 48 |
| Benton County | 336 | 19.6 | Very hard | 280 to 360 | 31 |
| Wayne County | 335 | 19.6 | Very hard | 310 to 351 | 321 |
| Steuben County | 333 | 19.5 | Very hard | 278 to 363 | 94 |
| Fayette County | 332 | 19.4 | Very hard | 310 to 350 | 147 |
| Randolph County | 331 | 19.3 | Very hard | 286 to 364 | 396 |
| Rush County | 331 | 19.3 | Very hard | 300 to 350 | 135 |
| Wells County | 330 | 19.3 | Very hard | 310 to 376 | 12 |
| Adams County | 327 | 19.1 | Very hard | 278 to 384 | 504 |
| Delaware County | 327 | 19.1 | Very hard | 277 to 360 | 514 |
| Warren County | 327 | 19.1 | Very hard | 290 to 350 | 193 |
| Hamilton County | 326 | 19 | Very hard | 290 to 360 | 150 |
| LaGrange County | 325 | 19 | Very hard | 280 to 370 | 22 |
| Boone County | 320 | 18.7 | Very hard | 282 to 336 | 82 |
| Grant County | 320 | 18.7 | Very hard | 279 to 350 | 358 |
| Switzerland County | 319 | 18.6 | Very hard | 210 to 450 | 5 |
| Montgomery County | 318 | 18.6 | Very hard | 288 to 348 | 374 |
| Johnson County | 316 | 18.5 | Very hard | 290 to 338 | 369 |
| Union County | 315 | 18.4 | Very hard | 290 to 336 | 20 |
| White County | 315 | 18.4 | Very hard | 289 to 335 | 84 |
| Shelby County | 310 | 18.1 | Very hard | 280 to 335 | 146 |
| Tipton County | 310 | 18.1 | Very hard | 280 to 364 | 57 |
| Vermillion County | 310 | 18.1 | Very hard | 280 to 338 | 581 |
| Marion County | 308 | 18 | Very hard | 258 to 360 | 1,930 |
| Carroll County | 307 | 17.9 | Very hard | 269 to 336 | 346 |
| Fountain County | 307 | 17.9 | Very hard | 260 to 350 | 303 |
| Cass County | 306 | 17.9 | Very hard | 267 to 340 | 433 |
| Newton County | 306 | 17.9 | Very hard | 256 to 332 | 313 |
| Noble County | 305 | 17.8 | Very hard | 250 to 370 | 32 |
| Morgan County | 303 | 17.7 | Very hard | 273 to 331 | 454 |
| Jasper County | 302 | 17.6 | Very hard | 236 to 334 | 205 |
| Bartholomew County | 300 | 17.5 | Very hard | 261 to 320 | 306 |
| Fulton County | 300 | 17.5 | Very hard | 270 to 330 | 460 |
| Hendricks County | 300 | 17.5 | Very hard | 268 to 320 | 210 |
| Pulaski County | 300 | 17.5 | Very hard | 283 to 322 | 99 |
| Tippecanoe County | 300 | 17.5 | Very hard | 261 to 340 | 581 |
| Huntington County | 298 | 17.4 | Very hard | 242 to 343 | 698 |
| DeKalb County | 297 | 17.4 | Very hard | 270 to 302 | 5 |
| Hancock County | 294 | 17.2 | Very hard | 246 to 318 | 807 |
| Howard County | 292 | 17.1 | Very hard | 255 to 330 | 345 |
| Allen County | 290 | 16.9 | Very hard | 245 to 331 | 930 |
| Vigo County | 290 | 16.9 | Very hard | 190 to 430 | 404 |
| Starke County | 288 | 16.8 | Very hard | 230 to 314 | 98 |
| Elkhart County | 286 | 16.7 | Very hard | 230 to 314 | 713 |
| Putnam County | 286 | 16.7 | Very hard | 248 to 322 | 238 |
| Parke County | 283 | 16.5 | Very hard | 248 to 312 | 713 |
| Decatur County | 280 | 16.4 | Very hard | 260 to 310 | 41 |
| Franklin County | 280 | 16.4 | Very hard | 250 to 307 | 329 |
| St. Joseph County | 280 | 16.4 | Very hard | 240 to 330 | 471 |
| Sullivan County | 280 | 16.4 | Very hard | 210 to 400 | 648 |
| Kosciusko County | 276 | 16.1 | Very hard | 238 to 320 | 315 |
| Knox County | 270 | 15.8 | Very hard | 218 to 320 | 434 |
| Wabash County | 266 | 15.5 | Very hard | 200 to 339 | 317 |
| Porter County | 262 | 15.3 | Very hard | 170 to 350 | 2,561 |
| Owen County | 260 | 15.2 | Very hard | 190 to 300 | 235 |
| Daviess County | 251 | 14.7 | Very hard | 214 to 282 | 280 |
| Miami County | 248 | 14.5 | Very hard | 216 to 296 | 335 |
| Clay County | 240 | 14 | Very hard | 130 to 400 | 819 |
| LaPorte County | 240 | 14 | Very hard | 170 to 296 | 247 |
| Pike County | 238 | 13.9 | Very hard | 188 to 304 | 428 |
| Greene County | 228 | 13.3 | Very hard | 150 to 290 | 382 |
| Posey County | 223 | 13 | Very hard | 188 to 251 | 412 |
| Dearborn County | 220 | 12.9 | Very hard | 190 to 250 | 210 |
| Lawrence County | 213 | 12.4 | Very hard | 147 to 265 | 737 |
| Gibson County | 210 | 12.3 | Very hard | 170 to 249 | 822 |
| Jackson County | 200 | 11.7 | Very hard | 150 to 294 | 361 |
| Ohio County | 189 | 11 | Very hard | 170 to 212 | 68 |
| Harrison County | 188 | 11 | Very hard | 166 to 206 | 146 |
| Martin County | 186 | 10.9 | Very hard | 149 to 228 | 193 |
| Jennings County | 183 | 10.7 | Very hard | 150 to 227 | 262 |
| Washington County | 180 | 10.5 | Hard | 142 to 206 | 157 |
| Ripley County | 177 | 10.3 | Hard | 146 to 208 | 85 |
| Orange County | 170 | 9.9 | Hard | 140 to 205 | 162 |
| Spencer County | 169 | 9.9 | Hard | 83 to 395 | 59 |
| Lake County | 168 | 9.8 | Hard | 140 to 348 | 2,425 |
| Jefferson County | 160 | 9.3 | Hard | 130 to 182 | 72 |
| Monroe County | 160 | 9.3 | Hard | 130 to 246 | 38 |
| Crawford County | 153 | 8.9 | Hard | 118 to 182 | 74 |
| Scott County | 145 | 8.5 | Hard | 100 to 170 | 30 |
| Vanderburgh County | 140 | 8.2 | Hard | 120 to 190 | 59 |
| Perry County | 130 | 7.6 | Hard | 113 to 144 | 536 |
| Clark County | 99 | 5.8 | Moderately hard | 82 to 140 | 56 |
| Dubois County | 96 | 5.6 | Moderately hard | 80 to 138 | 263 |
| Brown County | 65 | 3.8 | Moderately hard | 47 to 88 | 30 |
| Floyd County | 2 | 0.1 | Soft | 1 to 3 | 12 |
Source: Water Quality Portal (USGS, EPA and state agencies), waterqualitydata.us, retrieved 2026-09-19. 2,904,346 samples across 3,110 counties.
What this means for a household in Indiana
At 16.4 grains per gallon, a family of four would need a softener of about 40,000 grains to regenerate roughly weekly, using around 672 lb of salt a year. Size it for your own household.
87 of these counties include well samples, so the figures are a reasonable guide for private well water there. Municipal supplies in the same counties may be softer, because utilities often blend or treat.
Hardness follows geology rather than borders. Where a county sits on limestone or dolomite the water is hard; on granite, basalt or sandstone it is soft. That is why neighbouring counties in this table can differ by a factor of several.