HardWaterLab

How hard is my water?

Hardness by county from public water monitoring, in grains per gallon and mg/L.

Convert a hardness figure

Hardness is dissolved calcium and magnesium, and it is the reason for scale in a kettle, spots on glassware and soap that will not lather. It is measured as if it were all calcium carbonate, which is why the same water can be quoted as 10 grains per gallon or 171 mg/L and both are correct.

This is ambient water, not tap water. These figures come from samples taken from wells, streams and springs by USGS, EPA and state agencies. Municipal utilities treat, blend and sometimes soften water before it reaches a tap, so a city supply can be considerably softer than the ground beneath it. Treat this as a good guide for a private well and an approximate one for city water. Your utility's annual water quality report gives the real number for a municipal tap, and a test strip gives it for yours.

The scale

The USGS hardness classification, and how many US counties fall in each band
Classmg/LGrains per gallonCountiesWhat you notice
Soft0 to 600 to 3.5893No treatment needed. Soap lathers easily and there is no scale.
Moderately hard60 to 1203.5 to 7499Noticeable but usually tolerable. Some spotting on glassware.
Hard120 to 1807 to 10.5401Scale in kettles and on fixtures, more soap needed, shorter appliance life.
Very hardover 180over 10.51,317Persistent scale, water heater efficiency loss, most households soften.

Source: Water Quality Portal (USGS, EPA and state agencies), waterqualitydata.us, retrieved 2026-09-19. 2,904,346 samples across 3,110 counties.

The hardest counties in the country

Ranked by the median of all hardness samples recorded in the county.

The 25 hardest US counties by median ambient water hardness
CountyStatemg/LgpgSamplesClass
Willacy CountyTexas6,200362.224Very hard
Carteret CountyNorth Carolina4,800280.41,437Very hard
Childress CountyTexas4,800280.4533Very hard
Bristol CountyRhode Island4,650271.66Very hard
King CountyTexas4,290250.61,421Very hard
McIntosh CountyGeorgia3,700216.1458Very hard
Crockett CountyTexas3,580209.19Very hard
Hardeman CountyTexas3,100181.195Very hard
Pecos CountyTexas2,900169.4397Very hard
Cottle CountyTexas2,800163.6884Very hard
Foard CountyTexas2,700157.7301Very hard
Hall CountyTexas2,500146404Very hard
Knox CountyTexas2,470144.31,155Very hard
Ward CountyTexas2,460143.75Very hard
Kent CountyTexas2,400140.2361Very hard
Howard CountyTexas2,340136.7106Very hard
Reeves CountyTexas2,300134.4453Very hard
Harmon CountyOklahoma2,200128.5778Very hard
Newport CountyRhode Island2,182127.58Very hard
Stonewall CountyTexas2,130124.42,773Very hard
Fisher CountyTexas2,100122.737Very hard
Rosebud CountyMontana2,090122.116,390Very hard
Hudson CountyNew Jersey2,000116.860Very hard
Dickens CountyTexas2,000116.812Very hard
Kenedy CountyTexas2,000116.8131Very hard

And the softest

The 25 softest US counties by median ambient water hardness
CountyStatemg/LgpgSamplesClass
Scott CountyKansas10.11,198Soft
Hancock CountyMississippi10.1365Soft
Wilkinson CountyMississippi10.1169Soft
Floyd CountyIndiana20.112Soft
Crawford CountyKansas20.11,772Soft
Perry CountyMississippi20.1588Soft
Franklin cityVirginia30.28Soft
Tuolumne CountyCalifornia30.2410Soft
Towns CountyGeorgia40.2451Soft
Bennington CountyVermont40.2964Soft
Fannin CountyGeorgia50.3719Soft
Lumpkin CountyGeorgia50.3984Soft
Marion CountyGeorgia50.362Soft
Rabun CountyGeorgia50.3848Soft
Taylor CountyGeorgia50.3288Soft
Harrison CountyMississippi50.3577Soft
Hamilton CountyNew York50.32,766Soft
Transylvania CountyNorth Carolina50.3875Soft
Aiken CountySouth Carolina50.3844Soft
Lee CountySouth Carolina50.3278Soft
Oconee CountySouth Carolina50.31,364Soft
Windham CountyVermont50.31,047Soft
Dawson CountyGeorgia60.4245Soft
Peach CountyGeorgia60.421Soft
Schley CountyGeorgia60.425Soft

Every state, county by county.

Frequently asked questions

What is a good water hardness level?
Below 60 mg/L (about 3.5 grains per gallon) is soft and needs nothing. Between 60 and 120 is moderately hard and usually tolerable. Above 180 mg/L, roughly 10.5 grains per gallon, is very hard, and that is where most households decide softening is worth it.
How do I find out how hard my water is?
Three ways, in increasing order of accuracy: this site for the ambient water in your county, your utility’s annual water quality report for a municipal supply, and a test strip or laboratory test for your own tap. A test strip costs very little and is the only one that measures your actual water.
Is hard water bad for you?
No. Hardness is a nuisance characteristic rather than a health one, and calcium and magnesium in drinking water are not harmful. The costs of hard water are scale in pipes and water heaters, shorter appliance life, more soap and detergent, and spotting on glass and fixtures.
What is the difference between grains per gallon and ppm?
One grain per gallon equals 17.118 mg/L, and mg/L and ppm are the same number. So 10 grains per gallon is 171 ppm. American water treatment uses grains, laboratory reports usually use mg/L, and the conversion is the source of a lot of confusion.

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