Well water in Onstad township, Minnesota

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Testing recommended

tested well samples in Onstad township exceeded the EPA limit for nitrate (10 mg/L), based on public data from USGS Water Quality Portal.

12 private wells tested 2018 to 2019 in state summaries; 158 test results across 5 contaminants from at least 4 wells, 2003 to 2015; nitrate has the most at 142. Data refreshed September 15, 2026.

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

What homeowner tests found

MDA Township Testing Program nitrate: private wells tested and reported to the state, 2018 to 2019. Shares are against the level the state applies to each contaminant, named in the last column; several are stricter than EPA.

Contaminant	Above state level	Wells tested	Median	95th pct	Highest	State level
Nitrate	0%	12				10 mg/L

What individual samples found

Each row summarizes every public sample for that contaminant inside Onstad township. 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
Nitrate 2003 to 2015	7%	142	58%	0.283	59.2	10 mg/L EPA limit

Sampled fewer than 10 times, too few to summarize: Chloride (4), Sodium (4), Manganese (4), Iron (4).

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	n/a	14%70 samples	0%72 samples	n/a

Nitrate above the limit in Onstad township fell from 14% of 70 samples in the 2000s to 0% of 72 in the 2010s.

Closer than the town

See the sampled wells near your address

The same records, drawn around one point: which wells within a few miles were sampled and what they found, how deep the wells next to you were drilled, and any leaking tank or cleanup site within a mile.

Check my address

What this means

Among homeowners in Onstad township who sent a sample to the state lab, no health-based limit was exceeded often enough to publish a share. That is good news, but a single well can still be the exception.

What to test for in Onstad township

1
Nitrate
7% of 142 local samples were above the limit.
2
Coliform bacteria
Recommended for every private well, every year.
3
Chloride
Detected in 100% of local samples.
4
Manganese
Detected in 100% of local samples.
5
Iron
Detected in 100% of local samples.

Test your Onstad township well for nitrate, coliform bacteria and chloride

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 Onstad township numbers, $29. Every line explained, ranked by what matters, with the fix for each.

The rock under Onstad township

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 town 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

Treatment that fits the local profile

Nitrate

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

Manganese

Oxidizing filter (greensand, birm) whole-house; Water softener (low levels); Point-of-use reverse osmosis

Iron

Oxidizing filter whole-house; Water softener (low levels); Aeration plus filtration

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 nitrate

Under-sink reverse osmosis system

under-sink or countertop, about $300

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

For nitrate

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 manganese

Iron and manganese oxidizing filter

whole-house, at the point of entry, about $1,800

Air-injection or greensand media; fixes staining at the source.

Free, no obligation

Get on the list for a free in-home water test in Onstad township

No water treatment company serves Onstad township through Well Water Nerd yet. We are signing licensed companies on county by county: they test at your tap for free, walk you through the numbers, and quote treatment only if something needs fixing. Leave your details and you are first in line. Nothing is shared until a company joins for Onstad township, and you get an email naming it first.

Common questions

How often should I test a private well in Onstad township?

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.

Towns near Onstad township

Closest first. Groundwater does not stop at a line on a map, so the next town over is a fair second opinion.

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

Sources

USGS Water Quality Portal: 158 samples in Onstad township. Data from the Water Quality Portal, a service of USGS, EPA and USDA; groundwater samples collected by USGS and cooperators. Retrieved September 3, 2026.
MDA Township Testing Program nitrate: summaries for 1 contaminants in Onstad township, up to 12 wells each. Nitrate results from the Minnesota Department of Agriculture Township Testing Program, 2013 to 2019, which offered a free test to every well in 344 townships with vulnerable groundwater. Townships were selected for vulnerable geology and row-crop land use, so their shares run above the state as a whole; county and state figures are not derived from them. Share is the final (follow-up) result above 10 mg/L as N. 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.