Water hardness by zip code
How hard is your water?
Water hardness is how much calcium and magnesium your water carries. Among the 50 largest US cities, tap water runs from 1 grain per gallon (13 mg/L) in Boston to 19 grains per gallon (317 mg/L) in Indianapolis. Across all US counties, about two in five have very hard water, over 180 mg/L.
Updated October 23, 2026. Data from USGS and EPA water samples and 44 city water utilities. How we made this
Your tap can be softer or harder than this if your water utility softens it or brings it in from somewhere else. Your utility's yearly water quality report has the exact number for your supply.
There aren't enough public water samples for for us to give a number. Your water utility's yearly water quality report (often called a Consumer Confidence Report) will list the hardness of your supply.
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US hard water map by county
Very hard water is the norm across the Midwest, where three in four counties are over 180 mg/L. The softest water is in New England and along the Southeast coast.
Each county is shaded by the median of its water samples. In 18 big-city counties we use the main water utility's own tap water figure instead. Tap or click a county to see its number.
- Soft 0 to 3.5 gpg (0 to 60 mg/L)
- Moderately hard 3.5 to 7 gpg (61 to 120 mg/L)
- Hard 7 to 10.5 gpg (121 to 180 mg/L)
- Very hard over 10.5 gpg (over 180 mg/L)
- No data not enough samples
Which states have the hardest water?
Each state's figure is the median of its county figures from public river, lake and well samples, so it describes the area's water, not any one utility's tap. States with fewer than 5 counties with enough samples are left out (47 states ranked).
| Rank | State | mg/L | gpg | Hardness | Counties with data |
|---|---|---|---|---|---|
| 1 | South Dakota | 434 | 25.4 | Very hard | 51 |
| 2 | North Dakota | 382 | 22.3 | Very hard | 53 |
| 3 | Iowa | 332 | 19.4 | Very hard | 88 |
| 4 | Indiana | 290 | 17.0 | Very hard | 88 |
| 5 | Ohio | 278 | 16.3 | Very hard | 88 |
| 6 | Illinois | 275 | 16.1 | Very hard | 101 |
| 7 | Nebraska | 260 | 15.2 | Very hard | 69 |
| 8 | Minnesota | 256 | 15.0 | Very hard | 87 |
| 9 | Kansas | 255 | 14.9 | Very hard | 97 |
| 10 | Utah | 253 | 14.8 | Very hard | 29 |
| 11 | Montana | 238 | 13.9 | Very hard | 56 |
| 12 | Oklahoma | 232 | 13.6 | Very hard | 76 |
| 13 | Wyoming | 205 | 12.0 | Very hard | 23 |
| 14 | Missouri | 200 | 11.7 | Very hard | 107 |
| 15 | Texas | 196 | 11.5 | Very hard | 142 |
| 16 | New Mexico | 192 | 11.2 | Very hard | 32 |
| 17 | Arizona | 190 | 11.1 | Very hard | 15 |
| 18 | Wisconsin | 168 | 9.8 | Hard | 66 |
| 19 | Idaho | 154 | 9.0 | Hard | 44 |
| 20 | Michigan | 150 | 8.8 | Hard | 80 |
| 21 | Colorado | 142 | 8.3 | Hard | 62 |
| 22 | California | 138 | 8.1 | Hard | 58 |
| 23 | Florida | 128 | 7.5 | Hard | 66 |
| 24 | New York | 126 | 7.4 | Hard | 60 |
| 25 | Nevada | 126 | 7.4 | Hard | 17 |
| 26 | Kentucky | 123 | 7.2 | Hard | 113 |
| 27 | Tennessee | 110 | 6.4 | Moderately hard | 95 |
| 28 | Alaska | 79 | 4.6 | Moderately hard | 24 |
| 29 | Pennsylvania | 78 | 4.6 | Moderately hard | 67 |
| 30 | West Virginia | 75 | 4.4 | Moderately hard | 55 |
| 31 | Oregon | 74 | 4.3 | Moderately hard | 36 |
| 32 | New Jersey | 68 | 4.0 | Moderately hard | 22 |
| 33 | Vermont | 66 | 3.9 | Moderately hard | 14 |
| 34 | Maryland | 64 | 3.7 | Moderately hard | 24 |
| 35 | Washington | 62 | 3.6 | Moderately hard | 32 |
| 36 | Connecticut | 60 | 3.5 | Soft | 8 |
| 37 | Louisiana | 56 | 3.3 | Soft | 63 |
| 38 | Maine | 52 | 3.0 | Soft | 14 |
| 39 | Arkansas | 51 | 3.0 | Soft | 75 |
| 40 | Alabama | 40 | 2.3 | Soft | 67 |
| 41 | Massachusetts | 40 | 2.3 | Soft | 12 |
| 42 | Virginia | 34 | 2.0 | Soft | 115 |
| 43 | Mississippi | 29 | 1.7 | Soft | 55 |
| 44 | North Carolina | 27 | 1.6 | Soft | 97 |
| 45 | Georgia | 24 | 1.4 | Soft | 159 |
| 46 | South Carolina | 21 | 1.2 | Soft | 46 |
| 47 | New Hampshire | 16 | 0.9 | Soft | 10 |
Water hardness in the 50 largest US cities
Tap water hardness in the main city of each of the 50 largest US metro areas, as published by that city's main water utility. Six of the 50 utilities don't publish a total hardness figure. Sort by any column.
Data: each utility's own water quality report or hardness page, linked on every row. Updated October 23, 2026.
| 1 | New York, NY | 32 | 2 | Soft | NYC Department of Environmental Protection | 2025 drinking water quality report |
|---|---|---|---|---|---|---|
| 2 | Los Angeles, CA | 157 | 9.2 | Hard | Los Angeles Department of Water and Power (LADWP) | 2025 drinking water quality report |
| 3 | Chicago, IL | 134 | 7.9 | Hard | Chicago Department of Water Management | 2025 water quality lab results |
| 4 | Dallas, TX | 138 | 8.0 | Hard | Dallas Water Utilities | December 2023 city council memo |
| 5 | Houston, TX | 136 | 7.9 | Hard | City of Houston Public Works (Houston Water) | 2025 water quality report |
| 6 | Miami, FL | Not published by the utility | Miami-Dade Water and Sewer Department | 2025 water quality report | ||
| 7 | Washington, DC | 139 | 8 | Hard | DC Water (water from Washington Aqueduct) | 2026 water quality report |
| 8 | Atlanta, GA | Not published by the utility | City of Atlanta Department of Watershed Management | Water quality reports | ||
| 9 | Philadelphia, PA | 140 | 8.2 | Hard | Philadelphia Water Department | 2025 drinking water quality report |
| 10 | Phoenix, AZ | 237 | 13.9 | Very hard | City of Phoenix Water Services Department | 2025 water quality report |
| 11 | Boston, MA | 13 | 1 | Soft | Boston Water and Sewer Commission (water supplied by MWRA) | Water quality page (2025 data) |
| 12 | Riverside, CA | 197 | 12 | Very hard | Riverside Public Utilities | 2025 water quality report |
| 13 | San Francisco, CA | 62 | 3.6 | Moderately hard | San Francisco Public Utilities Commission (SFPUC) | 2025 water quality report |
| 14 | Detroit, MI | 107 | 6.3 | Moderately hard | Detroit Water and Sewerage Department | 2025 water quality report |
| 15 | Seattle, WA | 28 | 1.6 | Soft | Seattle Public Utilities | May 2026 water analysis |
| 16 | Minneapolis, MN | 95 | 5.5 | Moderately hard | Minneapolis Water Treatment and Distribution | Late 2025 monthly water analyses |
| 17 | Tampa, FL | 211 | 12.3 | Very hard | City of Tampa Water Department | 2025 water quality report |
| 18 | San Diego, CA | 217 | 12.7 | Very hard | City of San Diego Public Utilities | 2025 drinking water quality report |
| 19 | Denver, CO | 105 | 6.1 | Moderately hard | Denver Water | 2026 water quality report |
| 20 | Orlando, FL | 129 | 7 | Hard | Orlando Utilities Commission (OUC) | Water quality page (undated) |
| 21 | Charlotte, NC | 32 | 1.9 | Soft | Charlotte Water | 2025 drinking water quality report |
| 22 | Baltimore, MD | 94 | 5.5 | Moderately hard | Baltimore City Department of Public Works | 2021 mineral analyses (the latest it publishes): Ashburton, Montebello |
| 23 | St. Louis, MO | 129 | 7.5 | Hard | City of St. Louis Water Division | 2025 water quality report |
| 24 | San Antonio, TX | 299 | 17.5 | Very hard | San Antonio Water System (SAWS) | Water quality FAQ page (undated) |
| 25 | Austin, TX | 93 | 5.4 | Moderately hard | Austin Water | 2025 water quality report |
| 26 | Portland, OR | 44 | 2.5 | Soft | Portland Water Bureau | 2026 drinking water quality report |
| 27 | Sacramento, CA | 83 | 4.9 | Moderately hard | City of Sacramento Department of Utilities | 2025 water quality report |
| 28 | Pittsburgh, PA | Not published by the utility | Pittsburgh Water (formerly PWSA) | 2025 water quality report | ||
| 29 | Las Vegas, NV | 280 | 16 | Very hard | Las Vegas Valley Water District | 2026 water quality report |
| 30 | Cincinnati, OH | 133 | 7.8 | Hard | Greater Cincinnati Water Works | 2025 water quality report |
| 31 | Kansas City, MO | 100 | 5.8 | Moderately hard | KC Water (Kansas City, Missouri) | Water quality topics page (undated) |
| 32 | Columbus, OH | 115 | 6.7 | Moderately hard | City of Columbus Division of Water | 2025 water quality report |
| 33 | Indianapolis, IN | 317 | 19 | Very hard | Citizens Energy Group (Citizens Water) | 2025 water quality report |
| 34 | Cleveland, OH | 117 | 6.8 | Moderately hard | Cleveland Water (Cleveland Division of Water) | 2025 water quality report |
| 35 | Nashville, TN | 100 | 5.9 | Moderately hard | Metro Water Services Nashville | 2025 water quality report (2023 hardness data) |
| 36 | San Jose, CA | 179 | 10.5 | Hard | San Jose Water | 2025 water quality report |
| 37 | Virginia Beach, VA | 61 | 3.6 | Moderately hard | City of Virginia Beach Public Utilities | 2026 water quality report |
| 38 | Jacksonville, FL | 256 | 15.0 | Very hard | JEA | Hardness by zip code page (undated) |
| 39 | Providence, RI | Not published by the utility | Providence Water | 2025 water quality report | ||
| 40 | Milwaukee, WI | 137 | 8.01 | Hard | Milwaukee Water Works | Hardness FAQ page (undated) |
| 41 | Raleigh, NC | 25 | 1.5 | Soft | City of Raleigh Public Utilities | 2025 water quality report |
| 42 | Oklahoma City, OK | Not published by the utility | Oklahoma City Utilities (Oklahoma City Water Utilities Trust) | 2025 water quality report | ||
| 43 | Louisville, KY | 128 | 7.5 | Hard | Louisville Water Company | 2025 water quality report |
| 44 | Richmond, VA | 81 | 4.7 | Moderately hard | City of Richmond Department of Public Utilities | 2025 water quality report |
| 45 | Memphis, TN | 48 | 2.8 | Soft | Memphis Light, Gas and Water (MLGW) | 2025 water quality report |
| 46 | Salt Lake City, UT | 171 | 10.0 | Hard | Salt Lake City Department of Public Utilities | 2026 water quality report |
| 47 | Birmingham, AL | 98 | 5.7 | Moderately hard | Birmingham Water Works | 2025 water quality report |
| 48 | Fresno, CA | 129 | 7.5 | Hard | City of Fresno Department of Public Utilities | 2025 water quality report |
| 49 | Grand Rapids, MI | 142 | 8.3 | Hard | City of Grand Rapids Water System | 2025 water analysis |
| 50 | Hartford, CT | Not published by the utility | Metropolitan District Commission MDC | 2025 water quality report | ||
Download the data (CSV)County medians for all 2,867 counties (CSV)
Where a utility publishes a system-wide average we show it. Where it publishes an average for each treatment plant or source but no overall figure, we show the mean of those averages. Where it gives only a range, we show the middle of the range. Grains per gallon are the utility's own figure where it prints one. Your tap can be anywhere in the utility's range.
How do you wash clothes in hard water?
Give clothes room to move
A packed drum doesn't rinse well. Leave about a hand's width at the top so water can carry detergent and minerals away.
Clean your washer every month or so
Hard water leaves scale inside the drum and hoses. A monthly cleaning cycle keeps your machine rinsing properly.
Our Washing Machine Cleaner Tablets are made for this. One tablet in the empty drum on the hottest cycle clears hard-water scale, detergent buildup and odor, in front and top loaders.
Think about a water softener
If your water is very hard, a home softener treats the water for the whole house, washer included.
HeySunday laundry sheets come pre-measured: 1 sheet for a small load (about a quarter of the drum), 2 for a medium load (about three quarters full) and 3 for an extra large or heavily soiled load.
Get up to 40% off with Subscribe & Save. Easily cancel or adjust at any time.
Hard water questions
What counts as hard water?
The USGS groups water by how much calcium and magnesium it holds, measured as calcium carbonate. 0 to 60 mg/L is soft, 61 to 120 is moderately hard, 121 to 180 is hard and anything over 180 is very hard.
How do I turn mg/L into grains per gallon?
Divide by 17.1. So 171 mg/L is 10 grains per gallon. Water softener makers usually quote grains per gallon.
Is my tap water the same as my county's number?
Not always. This map uses samples from rivers, lakes and wells in your county. If your utility softens the water or pipes it in from somewhere else, your tap can be softer or harder. Your utility's yearly Consumer Confidence Report has the exact figure. For the biggest cities we show the main water utility's own published tap water figure instead, with a link to its report.
Where does this data come from?
The Water Quality Portal, run by the USGS and the EPA, which brings together water samples from federal, state, tribal and local agencies. We used hardness results from 2000 onward, took the median for each sampling site, then the median of those sites for each county.
More laundry help
How we made this
Last updated October 23, 2026.
- County numbers. Hardness results from the Water Quality Portal (USGS, EPA and the National Water Quality Monitoring Council), 2000 to 2026, from 113,685 sampling sites, downloaded October 22, 2026. We took the median for each site, then the median of the sites in each county. Counties with fewer than three samples show as no data. 2,867 of 3,142 counties have a number.
- City numbers. For the 50 largest metro areas we read the main water utility's own water quality report or hardness page. 44 publish a total hardness figure. We show the published system-wide average. Where there is none but the utility gives an average for each treatment plant or source, we show the mean of those averages (Los Angeles, Philadelphia, San Diego, Baltimore, Cincinnati, San Jose, Salt Lake City, Jacksonville and the Minneapolis monthly figures). Otherwise we show the middle of the published range. Kansas City and Milwaukee block automated reads, so their figures were read from a search engine's copy of each utility's own page. Every result links the report.
- Zip codes. Matched to counties and cities with the US Census Bureau 2020 ZCTA to county and ZCTA to place relationship files. County boundaries are from the US Census Bureau.
- Hardness bands. The USGS scale: soft 0 to 60 mg/L, moderately hard 61 to 120, hard 121 to 180, very hard over 180. Grains per gallon are mg/L divided by 17.1.
Cite this data
Quoting these numbers? Please credit HeySunday with a link to this page. To link a section, add #cities for the city table or #map for the map.