Wyoming Water Hardness by County
Water in Wyoming has a median hardness of 243.5 mg/L as CaCO₃ — "very hard" on the USGS scale — based on 44,904 measurements at 5,538 monitoring stations. Campbell County has the state's hardest measured water (830 mg/L); Teton County the softest (55). Rank: #11 of the 50 states and D.C.
Wyoming water hardness map — what the numbers mean. Data verified 2026-07-22.
Of Wyoming's 23 measured counties, 18 very hard, 1 hard, 3 moderately hard, and 1 soft. The hardest are Campbell County (830 mg/L), Crook County (764), and Niobrara County (680). Teton County is the softest at 55 mg/L (soft).
About 82% of Wyoming's roughly 0.6 million residents in counties with gate-passing hardness data live where tap water is hard or worse.
Statewide, Wyoming's median works out to 14.2 grains per gallon and ranks #11 of the 50 states and D.C. Across 44,904 measurements at 5,538 stations — 10,320 of them since 2000 — the middle 80% of readings fall between 19 and 825 mg/L. The public record runs from 1905 to 2023.
See where Wyoming sits nationally on the national map, or what its number means on the hardness scale.
Download the Wyoming water hardness map (PNG) — Water hardness by county in Wyoming: 23 counties mapped from USGS/EPA data, statewide median 243.5 mg/L (very hard); darker counties have harder water.
By county
Water hardness by county
The table lists all 23 measured Wyoming counties, hardest first. Their medians span 830 mg/L in Campbell County to 55 in Teton County — a 15.1× range.
| County | Median | Band | Results | Sites | Newest |
|---|---|---|---|---|---|
| Campbell County | 830 | Very hard | 1,973 | 361 | 2023 |
| Crook County | 764 | Very hard | 1,044 | 93 | 2023 |
| Niobrara County | 680 | Very hard | 364 | 78 | 2015 |
| Weston County | 530 | Very hard | 563 | 120 | 2020 |
| Johnson County | 497 | Very hard | 3,607 | 210 | 2023 |
| Sheridan County | 400 | Very hard | 3,416 | 134 | 2022 |
| Big Horn County | 330 | Very hard | 3,139 | 232 | 2018 |
| Sweetwater County | 280 | Very hard | 5,427 | 483 | 2023 |
| Converse County | 270 | Very hard | 1,545 | 160 | 2023 |
| Washakie County | 270 | Very hard | 904 | 160 | 2022 |
| Goshen County | 260 | Very hard | 963 | 146 | 2012 |
| Platte County | 260 | Very hard | 643 | 55 | 2015 |
| Albany County | 240 | Very hard | 753 | 166 | 2022 |
| Hot Springs County | 240 | Very hard | 561 | 194 | 2016 |
| Uinta County | 220 | Very hard | 1,490 | 147 | 2014 |
| Natrona County | 210 | Very hard | 1,899 | 254 | 2023 |
| Lincoln County | 208 | Very hard | 2,003 | 315 | 2023 |
| Carbon County | 180 | Very hard | 3,075 | 454 | 2023 |
| Laramie County | 171 | Hard | 319 | 211 | 2015 |
| Fremont County | 91 | Moderately hard | 5,956 | 586 | 2023 |
| Sublette County | 79.8 | Moderately hard | 1,467 | 186 | 2023 |
| Park County | 60 | Moderately hard | 1,556 | 306 | 2023 |
| Teton County | 55 | Soft | 2,237 | 487 | 2023 |
ZIP codes
ZIP codes in Wyoming
The ZIP codes below are grouped by the Wyoming county each mostly falls within (by land area). Each ZIP takes that county's measured median — shown in the group header — so this is a ZIP-to-county guide, not a separate reading for every ZIP. To check the water system serving a specific address, use the lookup.
Key: a † after a ZIP means it has no mapped community water system — usually a private-well area. Plain ZIPs are served by a mapped community water system.
Campbell County · 830 mg/L · Very hard
82716†82718†82725†82727†82731†82732†82831†
Crook County · 764 mg/L · Very hard
82710†82711†82712†82714†82720†82721†82729†
Niobrara County · 680 mg/L · Very hard
82222†82225†82227†82242†
Weston County · 530 mg/L · Very hard
82701†82723†82730†
Johnson County · 497 mg/L · Very hard
82639†82640†82834†
Sheridan County · 400 mg/L · Very hard
82801†82832†82833†82835†82836†82837†82838†82839†82842†82844†82845†
Big Horn County · 330 mg/L · Very hard
82410†82411†82412†82420†82421†82422†82423†82426†82428†82431†82432†82434†82441†
Sweetwater County · 280 mg/L · Very hard
82322†82336†82901†82929†82932†82934†82935†82938†82942†82943†82945†
Converse County · 270 mg/L · Very hard
82224†82229†82633†82637†
Washakie County · 270 mg/L · Very hard
82401†82442†
Goshen County · 260 mg/L · Very hard
82212†82217†82218†82219†82221†82223†82240†82243†82244†
Platte County · 260 mg/L · Very hard
82201†82210†82213†8221482215†
Albany County · 240 mg/L · Very hard
82051†82052†82055†82058†82070†82072†82073†82083†82084†
Hot Springs County · 240 mg/L · Very hard
8243082443†
Uinta County · 220 mg/L · Very hard
82933†82936†82937†82939†82944†
Natrona County · 210 mg/L · Very hard
82601†82604†82609†82620†82630†82635†82636†82638†82643†8264482646†82648†
Lincoln County · 208 mg/L · Very hard
83101†8311083111†83112†83114†83116†83118†83119†83121†83122†83123†83124†83126†8312783128†
Carbon County · 180 mg/L · Very hard
82301†82321†82323†82324†82325†82327†82329†82331†82332†82334†82335†
Laramie County · 171 mg/L · Hard
82001†82005†82007†82009†82050†82053†82054†82059†82060†82061†82081†82082†
Fremont County · 91 mg/L · Moderately hard
82310†82501†82510†82512†82513†82514†82515†82516†82520†82523†82642†82649†
Sublette County · 79.8 mg/L · Moderately hard
82922†82923†82925†82941†83113†83115†
Park County · 60 mg/L · Moderately hard
82190†82414†82433†82435†82440†82450†
Teton County · 55 mg/L · Soft
83001†83011†83012†83013†83014†8302583414†
† 170 ZIP codes are not served by a mapped community water system — most are private-well areas. See well water hardness.
Source
Groundwater vs surface water
Wyoming's surface water measures harder than its groundwater — 270 mg/L across 37,563 samples versus 199 across 4,474, about 1.4× harder. For well owners that is the better side of a hard bargain: at 199 mg/L, Wyoming groundwater is still very hard, and most of the state's drinking water is pumped from it. Groundwater readings there run 17 to 910 mg/L across the middle 80% of samples. The comparison draws on 3,155 groundwater and 2,239 surface-water monitoring sites; 548 readings above 2,000 mg/L were logged but held out of the medians as outliers.
Groundwater (wells)
199 mg/L as CaCO₃ · 4,474 results at 3,155 stations.
Surface water (rivers, lakes)
270 mg/L as CaCO₃ · 37,563 results at 2,239 stations.
Surface water measures about 1.4× harder than groundwater here.
Chemistry
Water chemistry in Wyoming
Beyond the hardness number, Wyoming's water carries a fuller chemical signature — here is how its measured parameters compare to national benchmarks.
TDS
637 mg/L · n=8,933
637 mg/L — about 2.8× the national county median of 226, consistent with hard, mineral-rich water.
pH
8.2 pH · n=6,422
pH 8.2 — within the EPA secondary range of 6.5–8.5, on the alkaline side.
Alkalinity
191 mg/L as CaCO3 · n=11,304
191 mg/L — substantial buffering capacity, which resists pH swings.
Calcium : Magnesium
61 : 29.9 mg/L ≈ 2.04 : 1 · n=11,203
Calcium is about 55% of Wyoming's hardness (61 mg/L Ca to 29.9 mg/L Mg), a little more magnesium-rich than the national ~68% calcium share.
Parameter medians may include a small share of quality-control samples; the hardness lane is fully QC-filtered.
Aquifers
Major aquifers under Wyoming
3 aquifer systems supply much of Wyoming's measured groundwater.
- Paleozoic aquifers — median 259 mg/L across 513 samples at 328 sites: very hard.
- Alluvial aquifers — median 231 mg/L across 1,117 samples at 683 sites: very hard.
- Lower Tertiary aquifers — median 200 mg/L across 1,048 samples at 827 sites: very hard.
Together these systems account for 2,678 measured samples at 1,838 sites. Aquifer medians pool samples across a whole system and can mask local variation — see the national aquifer map for how these compare across states.
Trend
Hardness over time
Wyoming's decade median moved from 170 mg/L in the 1940s to 195.5 in the 2020s. Over the series, the decade median peaked at 316 mg/L in the 2000s and bottomed at 63 in the 1990s. Decade medians reflect where and what agencies sampled in each era, not just changes in the water itself.
Scale
Where Wyoming sits on the scale
On the USGS scale, Wyoming's 243.5 mg/L is very hard — 14.2 grains per gallon, well above the 180 mg/L very-hard cutoff — among the hardest water measured in the US.
At 243.5 mg/L (14.2 gpg), water-softener owners in Wyoming typically set their unit to this hardness — settings calculator.
Questions
Frequently asked questions
- Is Wyoming's water hard?
- Wyoming's median hardness is 243.5 mg/L as CaCO₃, "very hard" on the USGS scale and 1.74× the national county median of 140 mg/L. About 82% of residents in measured counties have hard-or-worse water.
- Which county in Wyoming has the hardest water?
- Campbell County, with a median of 830 mg/L as CaCO₃ across 1,973 measurements.
- Is well water harder than city water in Wyoming?
- Surface water measures harder here — about 1.4× the groundwater — so wells tend to run softer (groundwater 199 vs surface water 270 mg/L).
- How do I find my exact hardness in Wyoming?
- Search your ZIP on the lookup tool, read your utility's Consumer Confidence Report, or test at home with a kit.
- Is Wyoming's water harder than the national average?
- Yes. Wyoming's median of 243.5 mg/L is 1.74× the national county median of 140 mg/L, and Wyoming ranks #11 of the 50 states and D.C.
Compare
States with similar hardness
Two states measure closest to Wyoming's 243.5 mg/L: Nebraska at 232 mg/L and Kansas at 260 mg/L. Wyoming measures harder than 80% of states. Browse the full ranking on the statistics page.
More: hardness scale · check your address · national statistics · the national map.
By Marko Visic, MPharm, BSc Physics. Source: USGS/EPA Water Quality Portal — 44,904 Wyoming measurements. Data last verified . Methodology.
Cite this page: “Wyoming Water Hardness by County.” Hard Water Map. Retrieved 2026-07-22, https://hardwatermap.com/water-hardness/wyoming/