US Hard Water Map: Water Hardness by State and City (2026)
Last updated: November 6, 2026 · Data: TapWaterData (utility reports), USGS, EPA
This US hard water map shows that water hardness varies a lot across the United States. Nebraska, Kansas, Wisconsin, Michigan and Utah have the hardest tap water, with state medians above 10.5 grains per gallon (GPG). Oregon, Maine, Georgia, North Carolina and New Hampshire have the softest, under 2 GPG. In general, the Midwest, Great Plains and Southwest have hard water, while the Pacific Northwest, New England and the Southeast have soft water.
Below you will find a color-coded map, the hardest and softest states, a full table for all 50 states plus Washington, D.C., and real numbers for major cities, so you can see where your water likely stands and whether a water softener makes sense.
Key takeaways
- Hardest state: Nebraska, at a median of 17.4 GPG (298 mg/L)
- Softest states: Oregon and Maine, at 1.3 GPG (23 mg/L)
- Hardest big cities: Madison, Las Vegas, Henderson, Miami and Phoenix
- Hard water starts at: about 7 GPG (120 mg/L); very hard is above 10.5 GPG
- Your city can differ a lot from your state median, so always check your local water report
US Hard Water Map (Water Hardness by State)
Hover over or tap a state to see its water hardness.
Median tap water hardness by state. Darker states have harder water. Data: TapWaterData US Water Hardness Dataset (CC BY 4.0), September 2026.
Each state shows the median hardness of the cities with utility-reported data. A median is the middle value, so half of the measured cities are harder and half are softer. Private wells are not included.
Water Hardness Chart: What the Numbers Mean
Hardness is measured in milligrams per liter (mg/L, the same as parts per million) or grains per gallon (GPG). One GPG equals about 17.1 mg/L. The USGS uses these four levels:
| Level | mg/L (ppm) | Grains per gallon | What you will notice |
|---|---|---|---|
| Soft | 0 to 60 | 0 to 3.5 | Soap lathers easily, little or no scale |
| Moderately hard | 61 to 120 | 3.5 to 7 | Light spots on glasses, slow scale buildup |
| Hard | 121 to 180 | 7 to 10.5 | Visible scale, soap scum, spotty dishes |
| Very hard | Over 180 | Over 10.5 | Heavy scale, dry skin, shorter appliance life |
Not sure what hard water does to a home? Read our guide to what hard water is and its signs.
10 States With the Hardest Water
| # | State | Median hardness (gpg) | mg/L | Rating |
|---|---|---|---|---|
| 1 | Nebraska | 17.4 | 298 | Very hard |
| 2 | Kansas | 14.4 | 247 | Very hard |
| 3 | Wisconsin | 12.8 | 219 | Very hard |
| 4 | Michigan | 12.6 | 216 | Very hard |
| 5 | Utah | 11.0 | 188 | Very hard |
| 6 | Missouri | 10.4 | 178 | Hard |
| 7 | Minnesota | 9.4 | 160 | Hard |
| 8 | Montana | 9.3 | 159 | Hard |
| 9 | Arizona | 9.2 | 158 | Hard |
| 10 | Illinois | 9.2 | 157 | Hard |
Most of these states sit on top of limestone, dolomite and gypsum, or draw water from rivers that carry a lot of dissolved minerals. In these states, a water softener is common in many homes.
10 States With the Softest Water
| # | State | Median hardness (gpg) | mg/L | Rating |
|---|---|---|---|---|
| 1 | Oregon | 1.3 | 23 | Soft |
| 2 | Maine | 1.3 | 23 | Soft |
| 3 | Georgia | 1.6 | 27 | Soft |
| 4 | North Carolina | 1.7 | 30 | Soft |
| 5 | New Hampshire | 1.8 | 31 | Soft |
| 6 | Mississippi | 2.2 | 38 | Soft |
| 7 | Delaware | 2.2 | 38 | Soft |
| 8 | Arkansas | 2.2 | 38 | Soft |
| 9 | Washington | 2.3 | 39 | Soft |
| 10 | South Carolina | 2.4 | 41 | Soft |
Soft-water states mostly rely on rain, snowmelt and surface water that flows over hard rock like granite, which does not dissolve easily. Homes here rarely need a softener, although private wells can still be hard.
Water Hardness by State: Full Table
All 50 states plus Washington, D.C., in alphabetical order. The last column is a general guide for city water; your own home may differ.
| State | Median (GPG) | mg/L | Rating | Water softener? |
|---|---|---|---|---|
| Alabama | 3.4 | 58 | Soft | Usually not needed |
| Alaska | 6.8 | 117 | Moderately hard | Optional |
| Arizona | 9.2 | 158 | Hard | Often worth it |
| Arkansas | 2.2 | 38 | Soft | Usually not needed |
| California | 5.8 | 98 | Moderately hard | Optional |
| Colorado | 5.6 | 96 | Moderately hard | Optional |
| Connecticut | 3.1 | 53 | Soft | Usually not needed |
| Delaware | 2.2 | 38 | Soft | Usually not needed |
| District of Columbia | 6.8 | 117 | Moderately hard | Optional |
| Florida | 5.1 | 87 | Moderately hard | Optional |
| Georgia | 1.6 | 27 | Soft | Usually not needed |
| Hawaii | 5.3 | 91 | Moderately hard | Optional |
| Idaho | 7.1 | 121 | Hard | Often worth it |
| Illinois | 9.2 | 157 | Hard | Often worth it |
| Indiana | 7.9 | 135 | Hard | Often worth it |
| Iowa | 7.4 | 127 | Hard | Often worth it |
| Kansas | 14.4 | 247 | Very hard | Usually worth it |
| Kentucky | 6.4 | 110 | Moderately hard | Optional |
| Louisiana | 5.8 | 99 | Moderately hard | Optional |
| Maine | 1.3 | 23 | Soft | Usually not needed |
| Maryland | 4.7 | 81 | Moderately hard | Optional |
| Massachusetts | 2.7 | 46 | Soft | Usually not needed |
| Michigan | 12.6 | 216 | Very hard | Usually worth it |
| Minnesota | 9.4 | 160 | Hard | Often worth it |
| Mississippi | 2.2 | 38 | Soft | Usually not needed |
| Missouri | 10.4 | 178 | Hard | Often worth it |
| Montana | 9.3 | 159 | Hard | Often worth it |
| Nebraska | 17.4 | 298 | Very hard | Usually worth it |
| Nevada | 7.0 | 120 | Moderately hard | Optional |
| New Hampshire | 1.8 | 31 | Soft | Usually not needed |
| New Jersey | 5.4 | 93 | Moderately hard | Optional |
| New Mexico | 5.1 | 88 | Moderately hard | Optional |
| New York | 2.8 | 49 | Soft | Usually not needed |
| North Carolina | 1.7 | 30 | Soft | Usually not needed |
| North Dakota | 7.8 | 133 | Hard | Often worth it |
| Ohio | 6.5 | 111 | Moderately hard | Optional |
| Oklahoma | 7.9 | 135 | Hard | Often worth it |
| Oregon | 1.3 | 23 | Soft | Usually not needed |
| Pennsylvania | 5.3 | 90 | Moderately hard | Optional |
| Rhode Island | 2.5 | 42 | Soft | Usually not needed |
| South Carolina | 2.4 | 41 | Soft | Usually not needed |
| South Dakota | 7.1 | 122 | Hard | Often worth it |
| Tennessee | 4.3 | 74 | Moderately hard | Optional |
| Texas | 5.7 | 97 | Moderately hard | Optional |
| Utah | 11.0 | 188 | Very hard | Usually worth it |
| Vermont | 3.9 | 67 | Moderately hard | Optional |
| Virginia | 3.8 | 65 | Moderately hard | Optional |
| Washington | 2.3 | 39 | Soft | Usually not needed |
| West Virginia | 6.8 | 117 | Moderately hard | Optional |
| Wisconsin | 12.8 | 219 | Very hard | Usually worth it |
| Wyoming | 6.2 | 106 | Moderately hard | Optional |
Hardest and Softest Water in Major US Cities
A state median can hide big differences. Nevada has a median of 7.0 GPG, but Las Vegas, where most Nevadans live, is above 16 GPG. Here are some of the hardest and softest large cities, based on utility-reported data.
Major cities with very hard water
| City | Hardness (gpg) | mg/L | Rating |
|---|---|---|---|
| Madison, WI | 19.9 | 341 | Very hard |
| Henderson, NV | 16.5 | 282 | Very hard |
| Las Vegas, NV | 16.4 | 280 | Very hard |
| Miami, FL | 14.5 | 248 | Very hard |
| Phoenix, AZ | 13.9 | 237 | Very hard |
| Salt Lake City, UT | 13.5 | 231 | Very hard |
| San Diego, CA | 13.2 | 225 | Very hard |
| Lincoln, NE | 12.6 | 215 | Very hard |
| Lubbock, TX | 12.0 | 205 | Very hard |
| Corpus Christi, TX | 11.6 | 199 | Very hard |
| Jacksonville, FL | 11.1 | 189 | Very hard |
| San Jose, CA | 10.8 | 185 | Very hard |
Major cities with soft water
| City | Hardness (gpg) | mg/L | Rating |
|---|---|---|---|
| Hartford, CT | 0.9 | 16 | Soft |
| Boston, MA | 1.0 | 17 | Soft |
| Portland, OR | 1.2 | 20 | Soft |
| Atlanta, GA | 1.4 | 24 | Soft |
| Raleigh, NC | 1.5 | 25 | Soft |
| Charlotte, NC | 1.8 | 31 | Soft |
| Colorado Springs, CO | 2.1 | 36 | Soft |
| Newark, NJ | 2.2 | 37 | Soft |
| Memphis, TN | 2.4 | 40 | Soft |
| Providence, RI | 2.5 | 42 | Soft |
City values are utility-reported averages and can change from year to year, or between neighborhoods served by different water sources.
Why Water Hardness Varies Across the US
Water becomes hard when it moves through rock and soil and dissolves calcium and magnesium along the way. Three things decide how hard your water is:
- Geology: limestone, dolomite and chalk dissolve easily. Large parts of the Midwest, the Great Plains, Texas, Florida and the Southwest sit on these rocks.
- Groundwater vs. surface water: water from deep wells and aquifers has more time to pick up minerals than water from lakes, rivers and reservoirs fed by rain and snowmelt. Madison, Wisconsin, which uses groundwater, is much harder than nearby Milwaukee, which draws from Lake Michigan.
- Climate: in dry regions, water evaporates and leaves minerals behind, so rivers like the Colorado carry more dissolved minerals. That is why Las Vegas and Phoenix have very hard water.
What to Do About Your Water Hardness
- Soft (under 3.5 GPG): you usually do not need any treatment for hardness.
- Moderately hard (3.5 to 7 GPG): a softener is optional. Some families add one to protect a tankless water heater or reduce spotting. A salt-free water conditioner can also help with scale.
- Hard (7 to 10.5 GPG): a water softener is often worth it if you see scale, soap scum or dry skin. See how much a water softener costs.
- Very hard (over 10.5 GPG): a salt-based water softener is usually the best fix. Learn how to install a water softener and how to maintain it.
How to Find Your Water Hardness by Zip Code
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Fastest way: use our free water hardness by zip code lookup.
The map shows the big picture, but water hardness can change from one zip code to the next, because each utility uses its own water sources. To get the number for your address:
- Check your utility’s water quality report. Every community water system must publish a yearly Consumer Confidence Report (CCR). Search for your water utility’s name, or use the EPA’s CCR search, then look for “hardness” or for calcium and magnesium.
- Test at home. Test strips and drop kits cost a few dollars and take minutes. See our guide on how to test water hardness at home.
- Test your well. If you are on a private well, it is not covered by any utility report, so testing is the only way to know.
Frequently Asked Questions
Which state has the hardest water?
Nebraska has the hardest tap water of any state by median, at about 17.4 grains per gallon (298 mg/L). Kansas (14.4 GPG), Wisconsin (12.8 GPG), Michigan (12.6 GPG) and Utah (11.0 GPG) round out the top five.
Which state has the softest water?
Oregon and Maine have the softest tap water, both at a median of about 1.3 grains per gallon (23 mg/L). Georgia, North Carolina and New Hampshire are also very soft, all under 2 GPG.
Is Las Vegas water hard?
Yes. Las Vegas tap water is very hard, at about 16.4 grains per gallon (280 mg/L). It comes mostly from the Colorado River through Lake Mead, which carries a lot of dissolved minerals. Nevada’s state median is lower because many smaller systems have softer water.
Can water hardness be different within the same state?
Yes, very different. Hardness depends on each utility’s water source, so two nearby towns can have soft and very hard water. That is why it is best to check your own utility’s water quality report or test your water at home.
At what hardness should I get a water softener?
Most homeowners start to see scale and spotty dishes above about 7 grains per gallon (120 mg/L). Above 10.5 GPG (180 mg/L), a water softener is usually worth it. Below 3.5 GPG, you generally do not need one.
About This Data
State and city figures come from the TapWaterData US Water Hardness Dataset (CC BY 4.0), updated September 2026. It compiles hardness reported by water utilities in their Consumer Confidence Reports, or calculated from the calcium and magnesium they report. State values are the median of measured cities, and cities served by more than one utility use a population-weighted average. Private wells are excluded. Hardness levels follow the USGS classification.
Sources: TapWaterData: Water Hardness Map (dataset DOI 10.5281/zenodo.21315903, CC BY 4.0); USGS: Water hardness in the United States; EPA: Consumer Confidence Reports.
