Well water in Warren County, Iowa

Name: Private well water quality in Warren County, Iowa
Creator: Well Water Nerd
License: Public domain (US federal government data)

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Testing recommended

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

The strongest signal is radium (226 + 228): 15% of 27 local samples were above the limit, too few samples to carry the headline but first on the test list below.

1,163 test results across 13 contaminants from at least 71 wells, 1934 to 2014; nitrate has the most at 175. Data refreshed September 15, 2026.

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

An estimated 2,206 people in Warren County get their drinking water from a private well, per USGS 2015 county water use. That is about 5% of residents.

Separately, the USGS national arsenic model estimates that 28% of the 2,206 people on private wells in Warren County draw water above 10 ug/L (the model's range is 24% to 34%), from geology and well depth rather than local tests.

What individual samples found

Each row summarizes every public sample for that contaminant inside Warren County. 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
Radium (226 + 228) 1972 to 2014	15%	27	78%	1.21	7	5 pCi/L EPA limit
Nitrate 1934 to 2014	8%	175	79%	0.32	430	10 mg/L EPA limit
Fluoride 1934 to 2014	0%	160	100%	0.475	4	4 mg/L EPA limit
Arsenic 1971 to 2014	0%	56	7%	0	2	10 ug/L EPA limit
Copper 1971 to 2014	0%	56	36%	0	0.45	1.3 mg/L EPA limit
Lead 1971 to 2014	0%	56	11%	0	0	15 ug/L EPA limit
Chloride 1934 to 2014	no limit	161	99%	27	520	250 mg/L nuisance level
Manganese 1934 to 2014	no limit	159	62%	40	3,600	300 ug/L health guideline
Iron 1934 to 2014	no limit	158	91%	600	130,000	300 ug/L nuisance level
Sodium 1955 to 2014	no limit	149	100%	28	1,980	20 mg/L health guideline

Sampled fewer than 10 times, too few to summarize: Uranium (2), E. coli (1), Radon (3).

Closer than the county

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

The contaminants most often above their limit here are radium (226 + 228) (15% of 27 samples) and nitrate (8% of 175 samples). A well next door can differ sharply from yours because bedrock fractures, well depth and plumbing all matter, so these rates describe the area, not your tap.

Chloride, Manganese, and Iron are widespread in local groundwater. They are mainly a staining and taste problem, but high manganese also carries a health advisory for infants.

What to test for in Warren County

1
Radium (226 + 228)
15% of 27 local samples were above the limit.
2
Nitrate
8% of 175 local samples were above the limit.
3
Coliform bacteria
Recommended for every private well, every year.
4
Radon
Median local reading is 42 pCi/L.
5
Fluoride
Detected in 100% of local samples.
6
Chloride
Detected in 99% of local samples.
7
Iron
Detected in 91% of local samples.
8
Volatile organic compounds (VOCs)
91 leaking underground storage tank sites on record locally.
9
Metals panel
8 hazardous waste sites on record locally.

Test your Warren County well for radium (226 + 228), nitrate and coliform bacteria

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 Iowa: certified labs, state programs and prices.

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

The rock under Warren County

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 county centroid. A single well can sit in a different unit, especially near a boundary.

Official help in Iowa

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.

Private Well Program, Iowa DNR
LabCert - List of Certified Labs, Iowa DNR

Contamination sources on record in Warren County

Iowa DNR records 91 leaking underground storage tank sites and 8 hazardous waste sites in Warren County, among 117 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.

91: leaking underground storage tank sitesGasoline and heating oil that leaked from tanks move through groundwater as benzene, MTBE and other volatile organic compounds.
8: hazardous waste sitesSolvents, degreasers and metals from industrial sites can travel far in fractured bedrock.
9: other remediation projects
9: other solid waste facilities

Treatment that fits the local profile

Radium (226 + 228)

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

Nitrate

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

Fluoride

Point-of-use reverse osmosis; Activated alumina; Distillation

Iron

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

Manganese

Oxidizing filter (greensand, birm) whole-house; Water softener (low levels); 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 radium (226 + 228)

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 Warren County

No water treatment company serves Warren County 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 Warren County, and you get an email naming it first.

Common questions

Is there arsenic in well water in Warren County?

Arsenic was detected in 7% of 56 public well samples in Warren County, and 0% 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 often should I test a private well in Warren County?

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 near Warren County

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

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

Sources

USGS Water Quality Portal: 1,163 samples in Warren County. Data from the Water Quality Portal, a service of USGS, EPA and USDA; groundwater samples collected by USGS and cooperators. Retrieved September 3, 2026.
USGS national arsenic model (Ayotte 2017): estimated share of 2,206 people on private wells in Warren County 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.
Iowa DNR regulated sites: 117 regulated sites located in Warren County. Contaminated sites, solid waste facilities and leaking underground storage tank sites from the Iowa Department of Natural Resources. Retrieved September 18, 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.