Water hardness in Wyoming
Wyoming has a median ambient water hardness of 248 mg/L, which is 14.5 grains per gallon and classes as very hard. That is the middle of 46,181 samples across 23 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 Wyoming
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 |
|---|---|---|---|---|---|
| Campbell County | 881 | 51.5 | Very hard | 497 to 1,270 | 2,038 |
| Crook County | 767 | 44.8 | Very hard | 490 to 979 | 1,084 |
| Niobrara County | 660 | 38.6 | Very hard | 240 to 1,000 | 384 |
| Weston County | 600 | 35.1 | Very hard | 260 to 1,600 | 569 |
| Johnson County | 493 | 28.8 | Very hard | 306 to 661 | 3,744 |
| Sheridan County | 400 | 23.4 | Very hard | 250 to 590 | 3,541 |
| Big Horn County | 330 | 19.3 | Very hard | 240 to 430 | 3,163 |
| Sweetwater County | 280 | 16.4 | Very hard | 190 to 580 | 5,552 |
| Converse County | 270 | 15.8 | Very hard | 210 to 480 | 1,568 |
| Washakie County | 270 | 15.8 | Very hard | 200 to 351 | 918 |
| Goshen County | 260 | 15.2 | Very hard | 220 to 300 | 969 |
| Platte County | 260 | 15.2 | Very hard | 230 to 300 | 647 |
| Albany County | 240 | 14 | Very hard | 180 to 370 | 762 |
| Hot Springs County | 234 | 13.7 | Very hard | 110 to 320 | 569 |
| Natrona County | 220 | 12.9 | Very hard | 174 to 614 | 1,936 |
| Uinta County | 220 | 12.9 | Very hard | 130 to 370 | 1,496 |
| Lincoln County | 208 | 12.2 | Very hard | 165 to 250 | 2,028 |
| Carbon County | 180 | 10.5 | Hard | 102 to 373 | 3,156 |
| Laramie County | 170 | 9.9 | Hard | 131 to 230 | 328 |
| Fremont County | 80 | 4.7 | Moderately hard | 5 to 240 | 6,301 |
| Sublette County | 78 | 4.6 | Moderately hard | 9 to 160 | 1,523 |
| Park County | 59 | 3.4 | Soft | 24 to 160 | 1,591 |
| Teton County | 57 | 3.3 | Soft | 17 to 158 | 2,314 |
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 Wyoming
At 14.5 grains per gallon, a family of four would need a softener of about 32,000 grains to regenerate roughly weekly, using around 595 lb of salt a year. Size it for your own household.
23 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.