State Well Water Guide
Iowa Private Well Water Guide
About 35% of Iowans rely on private wells — roughly one million people — with the highest rates in rural agricultural counties that cover most of the state. Iowa faces one of the nation's most severe agricultural groundwater contamination challenges: nitrate concentrations in Iowa's shallow aquifers are among the highest in the country due to the state's intensive corn production and heavy nitrogen fertilizer use. Bacterial contamination from livestock and manure application, and naturally elevated uranium and radium in some Cambrian-Ordovician aquifer areas, are additional concerns. IDNR regulates well construction and the state has an active private well program.
Testing Guidance
Iowa DNR strongly recommends annual testing for coliform bacteria and nitrates for all private wells. Given the state's documented nitrate crisis, quarterly testing during the spring runoff period (March–June) is advisable for shallow wells near row crops. Well owners using deep Cambrian-Ordovician sandstone aquifers in northeast Iowa should test for radium and uranium. All livestock operation neighbors should test for bacteria and nitrates.
What to Test For in Iowa
Total coliform bacteria and E. coli — annual minimum; quarterly spring testing recommended
Nitrates — highest priority for all Iowa well owners; test annually at minimum
Radium and uranium — deep Cambrian-Ordovician aquifer wells in northeast Iowa
Atrazine and other agricultural herbicides — corn belt shallow wells
Iron and manganese — glacial drift aquifer wells statewide
Arsenic — some glacial outwash areas in north-central Iowa
Bacteria from manure — wells near confined animal feeding operations
Common Contamination Risks in Iowa
Nitrate contamination — Iowa has among the highest rates of wells exceeding the 10 mg/L nitrate MCL in the nation; a 2019 state survey found 9% of all tested private wells above the MCL, with rates exceeding 30% in some agricultural counties
Bacterial contamination from livestock operations — Iowa is a top hog, cattle, and poultry producing state; manure lagoon leaks and field application contaminate shallow wells
Atrazine from corn production — atrazine herbicide is frequently detected in Iowa groundwater, particularly shallow sand and gravel wells
Radium and uranium in northeast Iowa deep aquifers — the Cambrian-Ordovician sandstone has documented radioactivity in northeastern counties
Flooding — Iowa's frequent river flooding can inundate well heads and contaminate wells with bacteria and agricultural chemicals
Contaminant Guides Relevant to IA 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 Iowa
Use the Iowa state-certified laboratory program to find accredited labs for private well testing. Always verify current certification before submitting samples.
IA Certified Lab Directory ↗Iowa 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
IA Certified Labs ↗EPA guidance
EPA Private Wells Program ↗State lab directory
IA Certified Labs ↗Minimum Annual Tests
Plus state-specific contaminants listed above
Other State Guides