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Well water hardness in Washington County, Arkansas

9.8 gpg hard

Private wells in Washington County typically give hard water: the median well sampled by the U.S. Geological Survey has 9.8 gpg (168 mg/L as CaCO₃).

<6060–120120–180>180 mg/L

Wells differ a lot, even next door: one in ten sampled wells had less than 100 mg/L and one in ten more than 194 mg/L. The figure comes from 15 wells and 16 samples taken between 1993 and 2023 (half of them by 1994).

Most samples are older than ten years. Groundwater hardness comes from the rock the well is drilled into and changes slowly, but your own well can be quite different, so treat this as a regional indication and test your water.

On city or town water instead of a well? Your utility publishes its own figures: Springdale (4.4 gpg), Rogers (4.4 gpg), Bentonville (4.4 gpg).

What this hardness means for a well household

How to test your well in Arkansas

Hardness is only one part of a well test. Federal health agencies advise every private well owner to test regularly:

Use a certified laboratory: Arkansas Department of Health, Water Microbiology Laboratory (private well samples; page also names private labs).

Testing is your own responsibility: no state agency samples existing private wells routinely.

What a test costs (Arkansas Department of Health Water Microbiology Laboratory)

Total coliform and E. coli, private well sample$17

Prices as printed by the lab (2026-10-29); check the current fee before you send a sample. Arkansas Department of Health Water Microbiology Laboratory

If no local lab suits you, mail-in kits from certified labs test a wider panel at home; they cost more than a state or county lab.

Treating hard well water

Most households with hard well water install an ion-exchange softener. Test iron and manganese first: above about 0.3 mg/L iron a softener alone is not enough and an iron filter goes in front of it.

Nearby counties

Benton County7.7 gpgDelaware County, OK6.4 gpgCarroll County13 gpgBarry County, MO10 gpgCrawford County22.4 gpgNewton County, MO9.6 gpg

FAQ

How hard is well water in Washington County, Arkansas?

The median well sampled by the USGS in Washington County has 9.8 gpg (168 mg/L as CaCO₃), which is hard. One in ten wells had less than 100 mg/L and one in ten more than 194 mg/L.

Is my own well the same?

Not necessarily. Hardness depends on the rock layer your well draws from and on its depth, so neighbouring wells can differ by a factor of two or more. Only a test of your own water tells you.

How often should I test my well in Arkansas?

Every year for coliform bacteria, nitrate, total dissolved solids and pH (EPA and CDC advice), and after floods, repairs or a change in taste or smell. Hardness, iron and manganese once, and again before you buy a softener.

Do I need a water softener for my well?

Recommended if you have a water heater, boiler or tankless unit: it saves repairs and detergent.

Where does this figure come from?

From 16 samples of 15 wells measured by the U.S. Geological Survey between 1993 and 2023, retrieved from the Water Quality Portal. We publish a county only when at least 10 wells were sampled.

Source and method

Computed by Water Hardness Atlas from USGS National Water Information System samples (characteristic "Hardness, Ca, Mg", sites of type well, samples since 1980), retrieved 2026-10-29 through the Water Quality Portal. For each well we take the median of its samples, then the median of all wells in the county; wells above 1,000 mg/L (oil, gas or mine brines) are left out. USGS data are in the U.S. public domain. Water Quality Portal query

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