Well water in Arkansas

Name: Private well water quality in Arkansas
Creator: Well Water Nerd
License: Public domain (US federal government data)

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Testing recommended

tested well samples in Arkansas exceeded the EPA limit for nitrate (10 mg/L), based on public data from USGS Water Quality Portal.

34,760 test results across 13 contaminants from at least 5,628 wells, 1928 to 2026; chloride has the most at 9,616. Data refreshed September 15, 2026.

Compiled by Nick at Well Water Nerd from public records. How these pages are built

An estimated 144,444 people in Arkansas get their drinking water from a private well, per USGS 2015 county water use.

Separately, the USGS national arsenic model estimates that <1% of the 144,444 people on private wells in Arkansas draw water above 10 ug/L (the model's range is <1% to 1%), from geology and well depth rather than local tests.

What individual samples found

Each row summarizes every public sample for that contaminant inside Arkansas. Above limit means above the EPA maximum contaminant level; where EPA has no enforceable limit, the row shows a health guideline or nuisance level instead.

Contaminant	Above limit	Samples	Detected	Median	Highest	Limit
Nitrate 1928 to 2026	6%	4,042	84%	0.23	292	10 mg/L EPA limit
E. coli 1995 to 2016	6%	51	6%	0	2	0 MPN/100mL EPA limit
Arsenic 1962 to 2025	3%	1,621	36%	0	80	10 ug/L EPA limit
Lead 1953 to 2025	<1%	1,786	33%	0	200	15 ug/L EPA limit
Fluoride 1942 to 2020	<1%	2,826	95%	0.18	31	4 mg/L EPA limit
Copper 1951 to 2025	<1%	1,785	50%	0	1.4	1.3 mg/L EPA limit
Uranium 1968 to 2025	0%	466	31%	0	22	30 ug/L EPA limit
Radium (226 + 228) 1968 to 2016	0%	113	86%	0.29	2.5	5 pCi/L EPA limit
Chloride 1928 to 2025	no limit	9,616	100%	14	160,000	250 mg/L nuisance level
Iron 1928 to 2025	no limit	5,593	93%	510	621,000	300 ug/L nuisance level
Sodium 1928 to 2025	no limit	4,065	99%	21.7	85,000	20 mg/L health guideline
Manganese 1949 to 2025	no limit	2,683	89%	31.5	25,000	300 ug/L health guideline
Radon 1993 to 2016	no limit	113	99%	160	890	2,000 pCi/L health guideline

Over time

Share of samples above the limit by period. A cell needs ten samples to show; a comparison needs twenty in each period. Later periods sample fewer wells, and often the ones already known to have a problem.

Contaminant	before 2000	2000s	2010s	2020s
Nitrate	7%3,309 samples	1%92 samples	<1%458 samples	0%183 samples
Fluoride	<1%1,929 samples	<1%555 samples	0%336 samples	n/a
Lead	<1%647 samples	<1%564 samples	<1%532 samples	0%43 samples
Copper	<1%646 samples	0%564 samples	0%532 samples	0%43 samples
Arsenic	6%549 samples	2%519 samples	2%510 samples	5%43 samples
Uranium	0%95 samples	0%22 samples	0%306 samples	0%43 samples

Nitrate, fluoride, lead, copper, arsenic, uranium have held within a few points between the two most recent periods with enough samples.

What this means

The contaminants most often above their limit here are nitrate (6% of 4,042 samples), e. coli (6% of 51 samples), and arsenic (3% of 1,621 samples). A well next door can differ sharply from yours because bedrock fractures, well depth and plumbing all matter, so these rates describe the area, not your tap.

Chloride, Iron, and Manganese are widespread in local groundwater. They are mainly a staining and taste problem, but high manganese also carries a health advisory for infants.

What to test for in Arkansas

1
Nitrate
6% of 4,042 local samples were above the limit.
2
E. coli
6% of 51 local samples were above the limit.
3
Arsenic
3% of 1,621 local samples were above the limit.
4
Lead
<1% of 1,786 local samples were above the limit.
5
Fluoride
<1% of 2,826 local samples were above the limit.
6
Copper
<1% of 1,785 local samples were above the limit.
7
Radon
Median local reading is 160 pCi/L.
8
Volatile organic compounds (VOCs)
5,610 hazardous waste sites on record locally.
9
Metals panel
5,610 hazardous waste sites on record locally.

Test your Arkansas well for nitrate, E. coli and arsenic

Certified lab analysis of your own tap water, bottles and prepaid return shipping included. The Essential well panel covers arsenic, uranium, nitrate, lead, copper, manganese, iron, sodium and bacteria; radon and PFAS are add-ons.

Order the Tap Score well water test kit, from $209 Already tested? Upload the report

Just want bacteria checked first? Tap Score coliform and E. coli test, $99. Coliform and E. coli are the tests every well needs every year.

Want a quick look before paying for a lab? Home well water test strips on Amazon check hardness, iron, pH and nitrate in minutes. They are a screen, not a result: arsenic, bacteria, uranium and PFAS need a certified lab.

Affiliate links: the merchant pays us a commission and the price is the same for you. It does not change what the data above says. As an Amazon Associate we earn from qualifying purchases.

Where to get a well tested in Arkansas: certified labs, state programs and prices.

Already have results back? Get your lab report read against the Arkansas numbers, $29. Every line explained, ranked by what matters, with the fix for each.

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Send me the Arkansas report

The numbers above, which tests to order and where, and the treatment that fits the local profile, in one email.

The rock under Arkansas

Mississippi River Valley alluvial aquifer

Unconsolidated sand and gravel. Wells in sand and gravel are usually shallow and productive, and they recharge quickly from the surface. That makes them the most exposed to nitrate, bacteria and anything spilled nearby, and the least likely to carry arsenic or radon from the rock.

Classification from the USGS Principal Aquifers of the United States (national map, 2003 edition, GIS release 2015), read at the state centroid. A single well can sit in a different unit, especially near a boundary.

Official help in Arkansas

Two places to start that are not selling anything: the state program that answers private well questions, and its list of labs certified to run drinking water tests. A certified lab is the difference between a result you can act on and a number.

Water Microbiology Laboratory, Arkansas Department of Health

Contamination sources on record in Arkansas

Arkansas DEQ permitted sites records 5,610 hazardous waste sites in Arkansas, among 13,112 regulated sites in total. Groundwater does not follow property lines, so a well within a few hundred feet of one of these is worth testing for what that site could release.

5,610: hazardous waste sitesSolvents, degreasers and metals from industrial sites can travel far in fractured bedrock.
6,612: registered underground storage tank sitesRegistered tanks are regulated and inspected; they matter most when they are old or near a shallow well.
890: lined landfills and transfer facilities

Treatment that fits the local profile

Nitrate

Point-of-use reverse osmosis; Anion exchange; Distillation

E. coli

Shock chlorination and fix the well cap or casing; UV disinfection whole-house; Chlorination system

Arsenic

Point-of-use reverse osmosis; Adsorptive media (iron-based) whole-house; Anion exchange

Lead

Point-of-use reverse osmosis; Certified lead-removal carbon filter; Neutralizing filter to raise pH and stop leaching

Fluoride

Point-of-use reverse osmosis; Activated alumina; Distillation

Systems we would look at first

Some links below are affiliate links. If you buy through one, the merchant pays us a commission at no extra cost to you. It does not change which products we list or what the data says.

For nitrate

Under-sink reverse osmosis system

under-sink or countertop, about $300

Look for NSF/ANSI 58 certification listing the contaminant you need removed.

For nitrate

Aquasana SmartFlow reverse osmosis

under-sink or countertop, about $225

Certified to NSF/ANSI 58 and 53 to reduce arsenic (96%, pentavalent), fluoride (90%), lead (99%), nitrate, nitrite and PFOA/PFOS at the kitchen tap, with a remineralizer.

For E. coli

UV disinfection system

whole-house, at the point of entry, about $900

Fix the well cap and casing first; UV keeps bacteria from returning.

For E. coli

Aquasana Rhino Well Water with UV

whole-house, at the point of entry, about $2,871

Whole-house system built for wells: sediment pre-filter, KDF and carbon, and a UV lamp rated to kill 99.99% of bacteria and viruses. It does not remove arsenic, nitrate, uranium or radon.

For arsenic

Whole-house arsenic and uranium filter

whole-house, at the point of entry, about $2,500

Adsorptive iron-based media; sized to your well yield.

For lead

Aquasana Claryum 3-Stage under-sink filter

under-sink or countertop, about $175

Certified to NSF/ANSI 53 to reduce 99% of lead and 99.7% of PFOA and PFOS at the tap. Not a fix for arsenic, nitrate or bacteria.

For lead

Acid neutralizing filter

whole-house, at the point of entry, about $1,200

Raises pH so plumbing stops leaching lead and copper.

Common questions

Is there arsenic in well water in Arkansas?

Arsenic was detected in 36% of 1,621 public well samples in Arkansas, and 3% were above the EPA limit of 10 ug/L. Arsenic has no taste or smell; a lab test is the only way to know your level.

How high is radon in well water in Arkansas?

The median radon level across 113 public samples in Arkansas was 160 pCi/L, with a high of 890 pCi/L. New Hampshire recommends treatment above 2,000 pCi/L.

How often should I test a private well in Arkansas?

Test for bacteria and nitrate every year. Test once for arsenic, uranium, radon, fluoride, manganese and PFAS, then again every three to five years or after any change in taste, color, or plumbing.

Counties in Arkansas

Want the numbers themselves? Download the Arkansas dataset as CSV, every county and town, with the sources named.

Sources

USGS Water Quality Portal: 34,760 samples in Arkansas. Data from the Water Quality Portal, a service of USGS, EPA and USDA; groundwater samples collected by USGS and cooperators. Retrieved September 3, 2026.
USGS national arsenic model (Ayotte 2017): estimated share of 144,444 people on private wells in Arkansas above 10 ug/L of arsenic, from geology, well depth and land use. County estimates of domestic well users with arsenic above 10 ug/L from the USGS national logistic regression model (Ayotte, Medalie and Qi, 2017), with private well population from the USGS 2015 county water-use compilation (Dieter and others, 2018). Retrieved September 15, 2026.
Arkansas DEQ permitted sites: 13,112 regulated sites located in Arkansas. Regulated storage tank, hazardous waste and solid waste permit sites from the Arkansas Division of Environmental Quality, through the Arkansas GIS Office. Retrieved September 18, 2026.

Non-detects count as samples and are treated as zero when computing medians. Exactly at the limit counts as not above it. A sample belongs to the town containing the well's reported coordinates.