Hard Water Map

Utah Water Hardness by County

Water in Utah has a median hardness of 270 mg/L as CaCO₃ — "very hard" on the USGS scale — based on 138,737 measurements at 13,140 monitoring stations. Emery County has the state's hardest measured water (660 mg/L); Wasatch County the softest (166.1). Rank: #8 of the 50 states and D.C.

Utah water hardness map — what the numbers mean. Data verified 2026-07-22.

Every one of Utah's 29 measured counties tests hard or harder: 28 rank very hard and 1 rank hard. The hardest are Emery County (660 mg/L), Millard County (450), and Grand County (380). Even Wasatch County, the softest measured area in the state, reads 166.1 mg/L — still hard on the USGS scale.

About 100% of Utah's roughly 3.3 million residents in counties with gate-passing hardness data live where tap water is hard or worse.

Statewide, Utah's median works out to 15.8 grains per gallon and ranks #8 of the 50 states and D.C. Across 138,737 measurements at 13,140 stations — 49,867 of them since 2000 — the middle 80% of readings fall between 102.7 and 733.5 mg/L. The public record runs from 1900 to 2023.

See where Utah sits nationally on the national map, or what its number means on the hardness scale.

Download the Utah water hardness map (PNG) — Water hardness by county in Utah: 29 counties mapped from USGS/EPA data, statewide median 270 mg/L (very hard); darker counties have harder water.

By county

Water hardness by county

The table lists all 29 measured Utah counties, hardest first. Their medians span 660 mg/L in Emery County to 166.1 in Wasatch County — a 4× range.

County water hardness, hardest first — median mg/L as CaCO₃.
CountyMedianBandResultsSitesNewest
Emery County660Very hard10,4257812023
Millard County450Very hard2,7894522021
Grand County380Very hard6,9734372023
Juab County375.9Very hard2,2763522021
Sanpete County369.2Very hard2,4542652021
Kane County343.7Very hard4,1003732021
Salt Lake County341.7Very hard11,9541,1532023
Wayne County330.4Very hard2,4012772021
Box Elder County318.2Very hard5,8454962023
Uintah County310Very hard10,9759072023
San Juan County290Very hard7,7868192023
Davis County289.1Very hard4,7572612023
Carbon County285Very hard3,1894002015
Washington County283.4Very hard3,7273912023
Tooele County283.1Very hard2,2027872021
Utah County263.5Very hard9,7768502021
Daggett County250Very hard1,889872023
Morgan County240Very hard1,8591902015
Rich County240Very hard837552015
Cache County235Very hard5,2673122021
Iron County233.5Very hard1,6643672021
Duchesne County220Very hard5,7065222023
Sevier County198.9Very hard2,9473352021
Garfield County198.1Very hard5,0214732021
Piute County192Very hard1,5371102021
Weber County190.6Very hard2,2972712023
Beaver County190Very hard2,5925402021
Summit County188Very hard6,4304692015
Wasatch County166.1Hard9,0624082023

ZIP codes

ZIP codes in Utah

The ZIP codes below are grouped by the Utah 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.

Emery County · 660 mg/L · Very hard

84513†84516†84518†84521†84522†84523†84525†84528†84537†

Millard County · 450 mg/L · Very hard

84624†84631†84635†84636†84637†84638†84640†84644†84649†8465684728†

Grand County · 380 mg/L · Very hard

84515†84532†84540†

Juab County · 375.9 mg/L · Very hard

84628†84639†84645†84648†

Sanpete County · 369.2 mg/L · Very hard

8462184622†84623†8462784629†84630†84632†84634†84642†84643†84646†84647†84662†84665†84667†

Kane County · 343.7 mg/L · Very hard

84710†84729†84741†84755†84758†84762†

Salt Lake County · 341.7 mg/L · Very hard

84006†840098402084044†84047840658407084081840848408884092†84093840948409584096841018410284103841048410584106841078410884109†841118411284113841148411584116†8411784118841198412084121†84123841248412884129841388415084180

Wayne County · 330.4 mg/L · Very hard

84715†84734†8474784749†84773†84775†

Box Elder County · 318.2 mg/L · Very hard

843018430284306†84307†84309843118431284313†84314843168432484329†84330†84331†8433484336†84337†84340†

Uintah County · 310 mg/L · Very hard

84008†84026†84035†8403984063840768407884085†

San Juan County · 290 mg/L · Very hard

84511†84512†84530†84531†84533†84534†84535†84536†

Davis County · 289.1 mg/L · Very hard

8401084014†84015840258403784040†84041840548405684075†84087

Carbon County · 285 mg/L · Very hard

8450184520†84526†84529†84539†84542†

Washington County · 283.4 mg/L · Very hard

84722†84725†84733†84737†84738†84745847468475784763†84765†84767847708477484779†8478084781†84782†84783†8478484790

Tooele County · 283.1 mg/L · Very hard

84022†84029†84034†84069†84071†8407484080†84083†

Utah County · 263.5 mg/L · Very hard

84003†84004†84005840138404284043†84045†84057840588405984062†84097846018460284604†8460684626†84633†84651†8465384655†84660†84663†84664

Daggett County · 250 mg/L · Very hard

84023†84046†

Morgan County · 240 mg/L · Very hard

84018†84050†

Rich County · 240 mg/L · Very hard

84028†84038†84064†84086†

Cache County · 235 mg/L · Very hard

84304†84305†843088431884319†8432084321†8432284325†84326†8432784328†8433284333†84335†843388433984341

Iron County · 233.5 mg/L · Very hard

84714†84719†84720†8472184742†84753†84756†84760†84761†84772†

Duchesne County · 220 mg/L · Very hard

84001840028400784021†84027†84031†8405184052840538406684072†84073

Sevier County · 198.9 mg/L · Very hard

8462084652†84654†84657†84701†847118472484730†84739†84744†8475484766†

Garfield County · 198.1 mg/L · Very hard

8471684718†847268473584736†84759†84764†84776

Piute County · 192 mg/L · Very hard

84712†8472384732†84740†8474384750†

Weber County · 190.6 mg/L · Very hard

84067843108431584317†8440184403†8440484405†8440884414

Beaver County · 190 mg/L · Very hard

84713†84731†84751†84752†

Summit County · 188 mg/L · Very hard

82930†84017†84024†84033†84036†84055†8406084061†84098

Wasatch County · 166.1 mg/L · Hard

84032†84049†84082†

† 178 ZIP codes are not served by a mapped community water system — most are private-well areas. See well water hardness.

Check any ZIP's utility and hardness →

Source

Groundwater vs surface water

Utah's groundwater measures harder than its surface water — 296.2 mg/L across 14,011 samples versus 266 across 120,849, about 1.1× harder. Wells draw from groundwater, so well owners in Utah tend to see the harder number — 296.2 mg/L, very hard. Groundwater readings there run 106 to 890 mg/L across the middle 80% of samples. The comparison draws on 5,584 groundwater and 7,141 surface-water monitoring sites; 3,835 readings above 2,000 mg/L were logged but held out of the medians as outliers.

Groundwater (wells)

296.2 mg/L as CaCO₃ · 14,011 results at 5,584 stations.

Surface water (rivers, lakes)

266 mg/L as CaCO₃ · 120,849 results at 7,141 stations.

Groundwater measures about 1.1× harder than surface water here.

Chemistry

Water chemistry in Utah

Beyond the hardness number, Utah's water carries a fuller chemical signature — here is how its measured parameters compare to national benchmarks.

TDS

386 mg/L · n=46,102

386 mg/L — about 1.7× the national county median of 226, consistent with hard, mineral-rich water.

pH

8.2 pH · n=89,455

pH 8.2 — within the EPA secondary range of 6.5–8.5, on the alkaline side.

Alkalinity

184 mg/L as CaCO3 · n=35,729

184 mg/L — substantial buffering capacity, which resists pH swings.

Calcium : Magnesium

60.3 : 24.2 mg/L ≈ 2.49 : 1 · n=67,058

Calcium is about 60% of Utah's hardness (60.3 mg/L Ca to 24.2 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 Utah

3 aquifer systems supply much of Utah's measured groundwater.

  • Alluvial aquifers — median 434 mg/L across 92 samples at 28 sites: very hard.
  • Basin and Range carbonate-rock aquifers — median 381 mg/L across 61 samples at 28 sites: very hard.
  • Basin and Range basin-fill aquifers — median 333.5 mg/L across 749 samples at 266 sites: very hard.

Together these systems account for 902 measured samples at 322 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

1920s2020s396

Utah's decade median moved from 320 mg/L in the 1920s to 342 in the 2020s. Over the series, the decade median peaked at 396 mg/L in the 1950s and bottomed at 244 in the 1990s. Decade medians reflect where and what agencies sampled in each era, not just changes in the water itself.

Scale

Where Utah sits on the scale

On the USGS scale, Utah's 270 mg/L is very hard — 15.8 grains per gallon, well above the 180 mg/L very-hard cutoff — among the hardest water measured in the US.

SoftModerately hardHardVery hard60 · 3.5 gpg120 · 7.0 gpg180 · 10.5 gpg270 mg/L — Very hard
Harder than 77% of the 2,977 measured county medians.

At 270 mg/L (15.8 gpg), water-softener owners in Utah typically set their unit to this hardness — settings calculator.

Questions

Frequently asked questions

Is Utah's water hard?
Utah's median hardness is 270 mg/L as CaCO₃, "very hard" on the USGS scale and 1.93× the national county median of 140 mg/L. About 100% of residents in measured counties have hard-or-worse water.
Which county in Utah has the hardest water?
Emery County, with a median of 660 mg/L as CaCO₃ across 10,425 measurements. Even the softest, Wasatch County at 166.1 mg/L, is still "hard" on the USGS scale.
Is well water harder than city water in Utah?
Groundwater measures harder here — about 1.1× the surface water — so wells tend to run harder (groundwater 296.2 vs surface water 266 mg/L).
How do I find my exact hardness in Utah?
Search your ZIP on the lookup tool, read your utility's Consumer Confidence Report, or test at home with a kit.
Is Utah's water harder than the national average?
Yes. Utah's median of 270 mg/L is 1.93× the national county median of 140 mg/L, and Utah ranks #8 of the 50 states and D.C.

Compare

States with similar hardness

Two states measure closest to Utah's 270 mg/L: Ohio at 270 mg/L and Indiana at 280 mg/L. Utah measures harder than 86% of states. Browse the full ranking on the statistics page.

More: hardness scale · check your address · national statistics · the national map.

By . Source: USGS/EPA Water Quality Portal — 138,737 Utah measurements. Data last verified . Methodology.

Cite this page: “Utah Water Hardness by County.” Hard Water Map. Retrieved 2026-07-22, https://hardwatermap.com/water-hardness/utah/