Well water in Minnesota

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Testing recommended

private wells tested between 2008 and 2021 in Minnesota had arsenic above the EPA limit (10 ug/L), according to the Minnesota Department of Health.

The strongest signal is PFOS: 19% of 782 local samples were above the limit, too few samples to carry the headline but first on the test list below.

71,831 private wells tested 2008 to 2021 in state summaries; 122,002 test results across 15 contaminants from at least 10,405 wells, 1932 to 2025; chloride has the most at 19,594. Data refreshed September 15, 2026.

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

An estimated 1,176,917 people in Minnesota get their drinking water from a private well, per USGS 2015 county water use.

Separately, the USGS national arsenic model estimates that 7% of the 1,176,917 people on private wells in Minnesota draw water above 10 ug/L (the model's range is 5% to 9%), from geology and well depth rather than local tests.

What homeowner tests found

MDH new private well arsenic tests: private wells tested and reported to the state, 2008 to 2021. Shares are against the level the state applies to each contaminant, named in the last column; several are stricter than EPA. County and state figures combine the town summaries, weighted by wells tested; medians are not combined.

Contaminant	Above state level	Wells tested	Median	95th pct	Highest	State level
Arsenic	12%	71,831				10 ug/L

What individual samples found

Each row summarizes every public sample for that contaminant inside Minnesota. 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
PFOS 2005 to 2023	19%	782	22%	0	500	4 ng/L EPA limit
PFOA 2005 to 2025	19%	1,232	34%	0	1,200	4 ng/L EPA limit
Nitrate 1932 to 2024	14%	14,023	74%	0.24	588	10 mg/L EPA limit
Arsenic 1972 to 2025	13%	10,321	56%	0.3	340	10 ug/L EPA limit
Radium (226 + 228) 2000 to 2018	3%	262	75%	0.26	25	5 pCi/L EPA limit
Lead 1972 to 2025	2%	11,052	25%	0	944	15 ug/L EPA limit
Uranium 1979 to 2024	<1%	443	76%	0.37	45.6	30 ug/L EPA limit
Fluoride 1953 to 2025	<1%	11,482	83%	0.184	16	4 mg/L EPA limit
Copper 1967 to 2025	<1%	8,040	40%	0	2.7	1.3 mg/L EPA limit
E. coli 2004 to 2018	0%	77	0%	0	0	0 MPN/100mL EPA limit
Chloride 1932 to 2025	no limit	19,594	97%	9.5	32,200	250 mg/L nuisance level
Iron 1932 to 2025	no limit	16,147	77%	231	151,000	300 ug/L nuisance level
Sodium 1932 to 2025	no limit	15,026	100%	9.14	18,500	20 mg/L health guideline
Manganese 1953 to 2025	no limit	13,382	79%	70.2	406,000	300 ug/L health guideline
Radon 1981 to 2014	no limit	139	99%	271	2,700	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	16%9,287 samples	12%2,760 samples	9%1,964 samples	0%12 samples
Fluoride	<1%5,202 samples	<1%1,070 samples	0%2,817 samples	<1%2,393 samples
Lead	8%2,841 samples	<1%972 samples	<1%4,894 samples	<1%2,345 samples
Arsenic	25%2,239 samples	11%843 samples	10%4,894 samples	7%2,345 samples
Copper	<1%2,254 samples	0%971 samples	0%3,513 samples	0%1,302 samples
PFOA	n/a	20%721 samples	n/a	19%502 samples

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

What this means

Among homeowners in Minnesota who sent a sample to the state lab, the health-based limits most often exceeded were arsenic (12% of 71,831 wells). These are ordinary wells tested by their owners, so the shares are the best available picture of a typical well here, with one caveat: people test more often when they suspect a problem.

What to test for in Minnesota

1
PFOS
19% of 782 local samples were above the limit.
2
PFOA
19% of 1,232 local samples were above the limit.
3
Nitrate
14% of 14,023 local samples were above the limit.
4
Arsenic
13% of 10,321 local samples were above the limit.
5
Radium (226 + 228)
3% of 262 local samples were above the limit.
6
Lead
2% of 11,052 local samples were above the limit.
7
Uranium
<1% of 443 local samples were above the limit.
8
Volatile organic compounds (VOCs)
18,396 leaking underground storage tank sites on record locally.
9
Metals panel
533 hazardous waste sites on record locally.

Test your Minnesota well for PFOS, PFOA and nitrate

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 Minnesota: certified labs, state programs and prices.

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

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Send me the Minnesota report

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

Wells in Minnesota

310,400 domestic wells in Minnesota are on record with the state since 1901. 29% are drilled into bedrock, and the typical well is 118 feet deep (one in ten goes past 279 feet).

In a typical Minnesota well, bedrock starts about 100 feet down.

1900s

142

1910s

200

1920s

345

1930s

578

1940s

4,561

1950s

6,759

1960s

33,789

1970s

49,181

1980s

90,541

1990s

79,783

2000s

29,165

2010s

6,825

2020s

Find your own well's report

The state keeps the driller's report for most wells drilled since 1984. It tells you how deep your well is, where bedrock starts, and how much water it makes, which decides what treatment can work.

Open Minnesota Well Index and choose Water Well.
The record shows depth, casing, depth to bedrock, aquifer, static water level and the driller; new wells since 2008 also show the arsenic test result.

Wells drilled since 1974 have records; older wells appear only if a later owner reported them.

The rock under Minnesota

Not a principal aquifer

The USGS map places this area outside any principal aquifer, which usually means wells here draw from fractured bedrock or thin local deposits rather than a large regional aquifer. Bedrock wells of that kind are where arsenic, radon and uranium turn up, and yields vary from well to well.

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 Minnesota

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.

Wells and Borings, Minnesota Department of Health
Accredited Laboratories as Well Partners, Minnesota Department of Health

Contamination sources on record in Minnesota

MPCA records 18,396 leaking underground storage tank sites and 533 hazardous waste sites in Minnesota, among 44,433 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.

18,396: leaking underground storage tank sitesGasoline and heating oil that leaked from tanks move through groundwater as benzene, MTBE and other volatile organic compounds.
533: hazardous waste sitesSolvents, degreasers and metals from industrial sites can travel far in fractured bedrock.
16,376: registered underground storage tank sitesRegistered tanks are regulated and inspected; they matter most when they are old or near a shallow well.
3,465: lined landfills and transfer facilities
5,663: other remediation projects

Treatment that fits the local profile

Arsenic

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

PFOS

Granular activated carbon whole-house; Point-of-use reverse osmosis; Anion exchange

PFOA

Granular activated carbon whole-house; Point-of-use reverse osmosis; Anion exchange

Nitrate

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

Radium (226 + 228)

Water softener (cation exchange); Point-of-use reverse osmosis

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 arsenic

Under-sink reverse osmosis system

under-sink or countertop, about $300

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

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 arsenic

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 PFOS

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 PFOS

Whole-house PFAS carbon system

whole-house, at the point of entry, about $3,000

Granular activated carbon certified to NSF/ANSI 53 for PFOA and PFOS; replace media on schedule.

For PFOS

Aquasana HealthShield whole-house filter

whole-house, at the point of entry, about $2,099

Whole-house carbon system the maker certifies to reduce PFAS (PFOA and PFOS) and VOCs at every tap; a UV option adds bacteria protection.

Common questions

How deep are wells in Minnesota?

The typical domestic well in Minnesota is 118 feet deep, based on 310,400 wells reported to the state since 1901. One in ten is deeper than 279 feet. 29% are drilled into bedrock.

Is there arsenic in well water in Minnesota?

Arsenic was detected in 56% of 10,321 public well samples in Minnesota, and 13% 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 Minnesota?

The median radon level across 139 public samples in Minnesota was 271 pCi/L, with a high of 2,700 pCi/L. New Hampshire recommends treatment above 2,000 pCi/L.

How often should I test a private well in Minnesota?

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 Minnesota

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

Sources

USGS Water Quality Portal: 122,002 samples in Minnesota. Data from the Water Quality Portal, a service of USGS, EPA and USDA; groundwater samples collected by USGS and cooperators. Retrieved September 3, 2026.
MDH new private well arsenic tests: summaries for 1 contaminants in Minnesota, up to 71,831 wells each. Arsenic results for every new private well drilled and tested August 2008 to December 2021, reported to the Minnesota Department of Health by well contractors and published by county. Mandatory test on new wells only, so older wells are not represented; 64,793 wells statewide. Shares are against 10 ug/L, which MDH applies as its advice level. Median and 95th percentile published per county. Retrieved September 15, 2026.
USGS national arsenic model (Ayotte 2017): estimated share of 1,176,917 people on private wells in Minnesota 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.
Minnesota Well Index: 404,868 well records in Minnesota, 310,400 domestic. Well construction records from the Minnesota Well Index (Minnesota Department of Health), non-public-supply wells. Only aggregates are shown; owner names and addresses are never stored. Retrieved September 15, 2026.
MPCA regulated sites: 44,433 regulated sites located in Minnesota. Tank, leak, remediation, Superfund and landfill sites from the Minnesota Pollution Control Agency What's In My Neighborhood database. Retrieved September 15, 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.