State Well Water Guide
South Dakota Private Well Water Guide
About 45% of South Dakotans rely on private wells — one of the highest rates in the nation — reflecting the state's sparse rural population across vast agricultural and ranch lands. South Dakota's groundwater is shaped by its geology and land use: naturally occurring arsenic in the James River lowlands and glacial drift, nitrate from livestock and crop agriculture, naturally high sulfate and TDS from sedimentary rock, and uranium from the Black Hills' granitic geology. DENR regulates well construction and maintains a private well program.
Testing Guidance
DENR recommends annual testing for coliform bacteria and nitrates. All well owners should test for arsenic given the state's natural occurrence. Eastern SD well owners should prioritize nitrate testing from row crop agriculture. West River (Black Hills) well owners should test for uranium and radon from granitic geology. High-sulfate water affects many SD wells — baseline TDS and sulfate testing is recommended.
What to Test For in South Dakota
Total coliform bacteria and E. coli — annual minimum
Arsenic — documented natural occurrence in eastern SD glacial deposits and alluvial areas
Nitrates — eastern South Dakota corn and cattle areas
Uranium — Black Hills granitic rock wells
Radon — Black Hills wells
Sulfate and total dissolved solids — commonly elevated statewide from sedimentary geology
Iron and manganese — glacial drift and alluvial wells throughout the state
Fluoride — naturally elevated in some SD aquifer systems
Common Contamination Risks in South Dakota
Naturally occurring arsenic — the James River lowlands and glacial Lake Dakota basin sediments have some of the highest naturally occurring arsenic concentrations in the Great Plains
Uranium from granitic geology — the Black Hills' Precambrian granite contains uranium minerals that can leach into groundwater
Nitrate from agriculture — eastern SD corn and cattle production creates nitrogen loading to shallow aquifers
High sulfate and TDS — the state's sedimentary geology naturally produces high-mineral water in many areas
Fluoride in some aquifer systems — naturally elevated fluoride has been found in certain SD aquifer formations
Contaminant Guides Relevant to SD 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 South Dakota
Use the South Dakota state-certified laboratory program to find accredited labs for private well testing. Always verify current certification before submitting samples.
SD Certified Lab Directory ↗South Dakota 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
SD Certified Labs ↗EPA guidance
EPA Private Wells Program ↗State lab directory
SD Certified Labs ↗Minimum Annual Tests
Plus state-specific contaminants listed above
Other State Guides