State Well Water Guide
Arkansas Private Well Water Guide
About 32% of Arkansans rely on private wells, with the highest rates in the rural Ozarks, Ouachita Mountains, and agricultural Delta region. Arkansas faces diverse groundwater contamination challenges: Ozarks karst aquifers are highly vulnerable to surface contamination, Delta alluvial aquifers show agricultural contamination patterns similar to the Mississippi Delta, and naturally elevated arsenic and manganese are found throughout the Mississippi Alluvial Plain. ADEQ regulates well construction but does not mandate periodic testing for existing private wells.
Testing Guidance
ADEQ recommends annual testing for coliform bacteria and nitrates. Ozark Highland well owners should test quarterly for bacteria given karst recharge vulnerabilities. Delta region well owners should test for nitrates, arsenic, and iron/manganese. All well owners near poultry operations — Arkansas is a major poultry-producing state — should test for bacteria and nitrates after application seasons.
What to Test For in Arkansas
Total coliform bacteria and E. coli — annual minimum; quarterly for karst areas
Nitrates — Delta agricultural areas and areas near poultry operations
Arsenic — Delta alluvial aquifer wells; naturally elevated
Iron and manganese — Delta and Gulf Coastal Plain aquifer wells
Agricultural chemicals — wells adjacent to rice, soybean, and cotton fields in the Delta
PFAS — near Little Rock AFB and other Arkansas military facilities
pH — Ozark springs and karst aquifer wells
Common Contamination Risks in Arkansas
Karst aquifer vulnerability in the Ozarks — the Springfield Plateau and Salem Plateau karst systems have rapid, unfiltered recharge pathways; bacterial contamination from livestock and septic sources is the primary concern
Arsenic in the Mississippi Alluvial Plain — naturally occurring arsenic from reducing aquifer conditions; one of the more significant natural arsenic zones in the US
Agricultural contamination from poultry operations — Arkansas is the nation's largest chicken-producing state; poultry litter applied to fields contributes bacteria, nitrogen, and phosphorus to groundwater
Iron and manganese from alluvial sediments — naturally elevated throughout the Delta and Gulf Coastal Plain
Rice field drainage affecting shallow wells — rice paddy drainage and flooding cycles in east Arkansas affect nearby shallow wells
Contaminant Guides Relevant to AR Wells
PFAS
Synthetic Chemicals
EPA limit: 4 ppt
Lead
Heavy Metals
EPA limit: 15 ppb (action level)
Nitrates
Agricultural Chemicals
EPA limit: 10 mg/L
DBPs
Disinfection Byproducts
EPA limit: 80 µg/L (TTHMs) / 60 µg/L (HAA5)
Arsenic
Heavy Metals
EPA limit: 10 ppb
Hard Water
Minerals
EPA limit: No federal limit
Chlorine
Disinfection Chemicals
EPA limit: 4 mg/L (MRDL)
Microplastics
Emerging Contaminants
EPA limit: No federal limit
Bacteria
Microbial Contamination
EPA limit: Zero E. coli / < 1 coliform per 100 mL
Fluoride
Minerals
EPA limit: 4 mg/L (MCL) / 2 mg/L (Secondary MCL)
Chromium-6
Heavy Metals
EPA limit: 100 ppb (total chromium)
Copper
Heavy Metals
EPA limit: 1.3 mg/L (action level)
Radon
Radioactive Contaminants
EPA limit: No finalized MCL
Iron & Manganese
Minerals
EPA limit: 0.3 mg/L iron / 0.05 mg/L manganese (aesthetic SMCLs)
Atrazine
Agricultural Chemicals
EPA limit: 3 ppb (0.003 mg/L)
Uranium
Radioactive Contaminants
EPA limit: 30 µg/L (30 ppb)
Perchlorate
Industrial Chemicals
EPA limit: 0.056 mg/L (56 ppb)
VOCs
Industrial Chemicals
EPA limit: Varies by compound: benzene 5 ppb; TCE 5 ppb; PCE 5 ppb; vinyl chloride 2 ppb
Radium
Radioactive Contaminants
EPA limit: 5 pCi/L (combined Ra-226 + Ra-228)
Crypto & Giardia
Microbial Contamination
EPA limit: Zero (treatment technique standard)
Hydrogen Sulfide
Naturally Occurring Compounds
EPA limit: No MCL; Secondary MCL (aesthetic) of 0.05 mg/L
Selenium
Minerals
EPA limit: 50 ppb (0.05 mg/L)
Cadmium
Heavy Metals
EPA limit: 5 ppb (0.005 mg/L)
Mercury
Heavy Metals
EPA limit: 2 ppb (0.002 mg/L)
Barium
Heavy Metals
EPA limit: 2 mg/L
Find a Certified Lab in Arkansas
Use the Arkansas state-certified laboratory program to find accredited labs for private well testing. Always verify current certification before submitting samples.
AR Certified Lab Directory ↗Arkansas Well Water FAQs
Related Pages
Data Sources & Provenance
All data on this page is sourced from official U.S. government or public datasets.
Quick Reference
State program
AR Certified Labs ↗EPA guidance
EPA Private Wells Program ↗State lab directory
AR Certified Labs ↗Minimum Annual Tests
Plus state-specific contaminants listed above
Other State Guides