State Well Water Guide
Minnesota Private Well Water Guide
About 35% of Minnesotans — approximately 1.9 million people — rely on private wells. Minnesota has one of the most robust state private well programs in the nation, including a well disclosure requirement at real estate transfer and an extensive Drinking Water Protection Program. Primary groundwater concerns include nitrate contamination from corn and livestock agriculture in southern Minnesota, arsenic from iron-rich glacial sediments in specific regions, coliform bacteria, and PFAS from 3M's Twin Cities manufacturing operations — which contaminated eastern Metro wells and led to one of the largest PFAS settlements in U.S. history.
Testing Guidance
MDH recommends annual testing for coliform bacteria and nitrates for all Minnesota private wells. Southern Minnesota agricultural county well owners should prioritize nitrate testing. Eastern Twin Cities metro area well owners should test for PFAS. Wells in glacially deposited fine-grained sediments should test for arsenic. MDH provides free nitrate testing through the county extension system.
What to Test For in Minnesota
Total coliform bacteria and E. coli — annual minimum
Nitrates — southern Minnesota agricultural counties (Olmsted, Dodge, Mower, Fillmore, and adjacent counties are high-risk)
Arsenic — glacial sediment wells in specific regions (contact MDH for your county's risk level)
PFAS — eastern Twin Cities metro area (Washington, Ramsey, Dakota counties) and near military facilities
Iron and manganese — glacial drift wells throughout the state
Radon — northeastern Minnesota crystalline rock region
Volatile organic compounds — near Minneapolis-St. Paul industrial areas
Common Contamination Risks in Minnesota
Nitrate from corn and livestock agriculture — southeastern Minnesota has particularly high nitrate concentrations, driven by karst limestone geology that allows rapid aquifer recharge
PFAS from 3M manufacturing — 3M's Cottage Grove and Decatur, Alabama plants disposed of PFAS compounds in eastern Twin Cities area wells and groundwater; one of the most significant industrial PFAS contamination events in the nation
Arsenic from glacial sediments — specific glacially deposited iron-rich sediments contain naturally elevated arsenic
Bacterial contamination from agriculture and failing septic — agricultural density in southern MN and older rural infrastructure
Radon in northeastern Minnesota — the Canadian Shield's granite and metamorphic rocks in northeastern MN contain uranium-bearing minerals that contribute to radon
Contaminant Guides Relevant to MN 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 Minnesota
Use the Minnesota state-certified laboratory program to find accredited labs for private well testing. Always verify current certification before submitting samples.
MN Certified Lab Directory ↗Minnesota 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
MN Certified Labs ↗EPA guidance
EPA Private Wells Program ↗State lab directory
MN Certified Labs ↗Minimum Annual Tests
Plus state-specific contaminants listed above
Other State Guides