Well Water Hardness Map by County: Florida and California

Tap any highlighted county to explore local groundwater hardness levels compiled from official state & USGS water quality data.

Florida Well Water Hardness by County

• Soft under 60 mg/L (under 3.5 gpg)
• Moderately hard 60 to 120 mg/L (3.5 to 7 gpg)
• Hard 121 to 180 mg/L (7 to 10.5 gpg)
• Very hard over 180 mg/L (over 10.5 gpg)
• Limited data fewer than 20 wells sampled

All 67 Florida counties ranked by hardness

County	Median hardness	Wells
Sarasota County	38.4 gpgVery hard, 657 mg/L	90
Flagler County	30.9 gpgVery hard, 529 mg/L	32
Charlotte County	29.2 gpgVery hard, 499 mg/L	44
Brevard County	26.1 gpgVery hard, 446 mg/L	52
Lee County	25.6 gpgVery hard, 438 mg/L	80
St. Johns County	23.2 gpgVery hard, 396 mg/L	57
St. Lucie County	22.8 gpgVery hard, 390 mg/L	43
Manatee County	21.2 gpgVery hard, 362 mg/L	70
DeSoto County	20.5 gpgVery hard, 351 mg/L	61
Indian River County	18.9 gpgVery hard, 324 mg/L	37
Pinellas County	18.9 gpgVery hard, 324 mg/L	38
Collier County	18.7 gpgVery hard, 320 mg/L	285
Hendry County	18 gpgVery hard, 307 mg/L	37
Palm Beach County	17.8 gpgVery hard, 304 mg/L	105
Okeechobee County	17.4 gpgVery hard, 298 mg/L	36
Nassau County	17.1 gpgVery hard, 292 mg/L	33
Orange County	16.8 gpgVery hard, 287 mg/L	136
Broward County	16.4 gpgVery hard, 280 mg/L	51
Volusia County	16.1 gpgVery hard, 276 mg/L	128
Martin County	15.8 gpgVery hard, 269 mg/L	38
Miami-Dade County	15.3 gpgVery hard, 262 mg/L	173
Dixie County	14.9 gpgVery hard, 254 mg/L	55
Hillsborough County	14.1 gpgVery hard, 241 mg/L	179
Levy County	13.7 gpgVery hard, 235 mg/L	178
Gilchrist County	12.2 gpgVery hard, 208 mg/L	110
Wakulla County	12.2 gpgVery hard, 209 mg/L	45
Suwannee County	12.1 gpgVery hard, 207 mg/L	169
Taylor County	12.1 gpgVery hard, 207 mg/L	82
Hamilton County	12 gpgVery hard, 206 mg/L	50
Sumter County	11.9 gpgVery hard, 203 mg/L	45
Alachua County	11.5 gpgVery hard, 196 mg/L	120
Lafayette County	11.5 gpgVery hard, 196 mg/L	86
Baker County	10.7 gpgVery hard, 183 mg/L	23
Duval County	10.6 gpgVery hard, 181 mg/L	168
Pasco County	10.6 gpgVery hard, 181 mg/L	152
Hardee County	10.4 gpgHard, 178 mg/L	29
Osceola County	10.2 gpgHard, 174 mg/L	63
Columbia County	10.1 gpgHard, 173 mg/L	146
Marion County	9.9 gpgHard, 169 mg/L	175
Union County	9.8 gpgHard, 168 mg/L	28
Hernando County	9.6 gpgHard, 165 mg/L	63
Bradford County	9.3 gpgHard, 160 mg/L	28
Citrus County	9.3 gpgHard, 159 mg/L	101
Jefferson County	9.1 gpgHard, 155 mg/L	42
Polk County	9 gpgHard, 153 mg/L	188
Leon County	8.9 gpgHard, 153 mg/L	51
Seminole County	8.9 gpgHard, 153 mg/L	65
Madison County	8.6 gpgHard, 147 mg/L	86
Jackson County	7.7 gpgHard, 131 mg/L	72
Highlands County	7.5 gpgHard, 128 mg/L	71
Putnam County	7.1 gpgHard, 121 mg/L	52
Lake County	6.9 gpgModerately hard, 119 mg/L	108
Bay County	5.7 gpgModerately hard, 97 mg/L	36
Walton County	5.3 gpgModerately hard, 90 mg/L	40
Clay County	4.8 gpgModerately hard, 81 mg/L	71
Okaloosa County	2.1 gpgSoft, 36 mg/L	33
Escambia County	0.5 gpgSoft, 8 mg/L	29
Santa Rosa County	0.4 gpgSoft, 7 mg/L	35
Calhoun County	Limited data	10
Franklin County	Limited data	7
Gadsden County	Limited data	19
Glades County	Limited data	10
Gulf County	Limited data	19
Holmes County	Limited data	11
Liberty County	Limited data	7
Monroe County	Limited data	2
Washington County	Limited data	14

See every Florida county well water report

California Well Water Hardness by County

• Soft under 60 mg/L (under 3.5 gpg)
• Moderately hard 60 to 120 mg/L (3.5 to 7 gpg)
• Hard 121 to 180 mg/L (7 to 10.5 gpg)
• Very hard over 180 mg/L (over 10.5 gpg)
• Limited data fewer than 20 wells sampled

All 58 California counties ranked by hardness

County	Median hardness	Wells
San Luis Obispo County	31.1 gpgVery hard, 531 mg/L	53
Ventura County	29.5 gpgVery hard, 505 mg/L	65
Santa Barbara County	28.3 gpgVery hard, 484 mg/L	232
Stanislaus County	19.1 gpgVery hard, 327 mg/L	174
Orange County	18.8 gpgVery hard, 321 mg/L	80
San Benito County	18.5 gpgVery hard, 316 mg/L	34
Monterey County	16.6 gpgVery hard, 284 mg/L	80
Santa Clara County	15.3 gpgVery hard, 261 mg/L	60
San Diego County	15.1 gpgVery hard, 259 mg/L	211
Alameda County	13.9 gpgVery hard, 238 mg/L	59
Kern County	12.1 gpgVery hard, 206 mg/L	222
Santa Cruz County	11.9 gpgVery hard, 203 mg/L	38
Los Angeles County	11.5 gpgVery hard, 197 mg/L	484
Riverside County	10.6 gpgVery hard, 181 mg/L	374
Fresno County	10.5 gpgHard, 179 mg/L	150
Imperial County	9.8 gpgHard, 168 mg/L	71
San Joaquin County	9.7 gpgHard, 166 mg/L	145
Merced County	9.5 gpgHard, 162 mg/L	112
Tulare County	9.3 gpgHard, 159 mg/L	120
Siskiyou County	8.5 gpgHard, 146 mg/L	26
Yuba County	8 gpgHard, 137 mg/L	21
San Bernardino County	7.3 gpgHard, 125 mg/L	941
Sonoma County	7.3 gpgHard, 125 mg/L	115
Sacramento County	6.8 gpgModerately hard, 116 mg/L	87
Tehama County	6.7 gpgModerately hard, 114 mg/L	66
Mendocino County	6.5 gpgModerately hard, 110 mg/L	32
Butte County	6 gpgModerately hard, 103 mg/L	46
Mono County	5.8 gpgModerately hard, 100 mg/L	26
Madera County	5.3 gpgModerately hard, 91 mg/L	87
Lassen County	5.2 gpgModerately hard, 89 mg/L	20
Napa County	5.2 gpgModerately hard, 88 mg/L	52
Placer County	5.1 gpgModerately hard, 88 mg/L	42
Nevada County	4.6 gpgModerately hard, 79 mg/L	58
Inyo County	4.5 gpgModerately hard, 76 mg/L	26
Shasta County	4.3 gpgModerately hard, 73 mg/L	61
Kings County	3.8 gpgModerately hard, 64 mg/L	33
El Dorado County	3.2 gpgSoft, 55 mg/L	69
Alpine County	Limited data	2
Amador County	Limited data	16
Calaveras County	Limited data	13
Colusa County	Limited data	9
Contra Costa County	Limited data	0
Del Norte County	Limited data	7
Glenn County	Limited data	17
Humboldt County	Limited data	19
Lake County	Limited data	16
Marin County	Limited data	5
Mariposa County	Limited data	4
Modoc County	Limited data	16
Plumas County	Limited data	7
San Francisco County	Limited data	5
San Mateo County	Limited data	12
Sierra County	Limited data	0
Solano County	Limited data	8
Sutter County	Limited data	19
Trinity County	Limited data	10
Tuolumne County	Limited data	7
Yolo County	Limited data	13

See every California county well water report

Another well water risk that changes from county to county: Explore national radon hazard zones by county.

How to Read the Map

Hardness is the calcium and magnesium dissolved in water, reported as calcium carbonate. Labs give it in milligrams per liter (mg/L, the same as ppm), while softener makers size equipment in grains per gallon (gpg). One gpg equals 17.1 mg/L. The map uses the USGS classes: soft is under 60 mg/L, moderately hard is 60 to 120 mg/L, hard is 121 to 180 mg/L and very hard is over 180 mg/L. Above about 7 gpg, most households notice scale on fixtures, spotty dishes and shorter water heater life.

Where the Numbers Come From

Each county value comes from groundwater samples in the Water Quality Portal, the shared database of the USGS, the EPA and state agencies, for wells sampled since 2000. We take the median of each well first, so a well that was sampled many times does not outweigh the rest, and then the median across all wells in the county. That covers about 4,800 wells in Florida and 4,800 in California. Counties with fewer than 20 sampled wells are marked as limited data and show no number.

These are well samples, not city tap water. Cities often treat or blend their supply, so if you are on a public water system, use the hardness in your utility’s annual water quality report. Hardness can also change a lot between neighboring wells and depths, so a county median is a starting point, not a measurement of your well.

What to Do Next

• Look up hardness by ZIP code to see the county median for your address and the softener size it points to.
• Test your own well. A lab or a hardness test strip gives you the real number in a few minutes, and our well water testing guide explains which tests to order.
• Put your result into the water softener sizing calculator to find the grain capacity your household needs.