Well water in Iowa

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

1in9

Testing recommended

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

110,251 test results across 15 contaminants from at least 5,169 wells, 1910 to 2026; nitrate has the most at 17,792. Data refreshed September 15, 2026.

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

An estimated 494,022 people in Iowa 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 494,022 people on private wells in Iowa draw water above 10 ug/L (the model's range is 6% to 9%), from geology and well depth rather than local tests.

What individual samples found

Each row summarizes every public sample for that contaminant inside Iowa. 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 1911 to 2026	11%	17,792	72%	0.33	2,800	10 mg/L EPA limit
Radium (226 + 228) 1969 to 2017	7%	5,179	70%	1	61	5 pCi/L EPA limit
E. coli 2007 to 2018	5%	145	5%	0	21	0 MPN/100mL EPA limit
Arsenic 1966 to 2024	3%	5,807	20%	0	200	10 ug/L EPA limit
Fluoride 1920 to 2026	<1%	14,311	99%	0.35	1,000	4 mg/L EPA limit
Lead 1940 to 2024	<1%	5,732	9%	0	1,300	15 ug/L EPA limit
Copper 1966 to 2024	<1%	5,709	22%	0	14	1.3 mg/L EPA limit
Uranium 1979 to 2024	0%	326	80%	0.297	17.3	30 ug/L EPA limit
Iron 1910 to 2026	no limit	14,241	86%	493	200,000	300 ug/L nuisance level
Manganese 1920 to 2026	no limit	14,110	70%	40	29,000	300 ug/L health guideline
Chloride 1910 to 2026	no limit	13,318	95%	11	94,300	250 mg/L nuisance level
Sodium 1910 to 2026	no limit	13,011	100%	16	4,300	20 mg/L health guideline
Radon 1982 to 2014	no limit	558	79%	120	2,290	2,000 pCi/L health guideline

Sampled fewer than 10 times, too few to summarize: PFOS (6), PFOA (6).

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	10%14,791 samples	10%2,114 samples	18%568 samples	6%319 samples
Fluoride	<1%11,605 samples	<1%2,135 samples	0%411 samples	0%160 samples
Arsenic	2%4,180 samples	7%1,328 samples	3%295 samples	n/a
Lead	<1%4,172 samples	0%1,306 samples	0%250 samples	n/a
Copper	<1%4,174 samples	0%1,284 samples	0%247 samples	n/a
Radium (226 + 228)	13%2,076 samples	3%2,782 samples	4%321 samples	n/a

Nitrate above the limit in Iowa fell from 18% of 568 samples in the 2010s to 6% of 319 in the 2020s.

Fluoride, arsenic, lead, copper, radium (226 + 228) have held within a few points between the two most recent periods with enough samples.

What this means

The contaminants most often above their limit here are nitrate (11% of 17,792 samples), radium (226 + 228) (7% of 5,179 samples), and e. coli (5% of 145 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.

Iron, Manganese, and Chloride 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 Iowa

1
Nitrate
11% of 17,792 local samples were above the limit.
2
Radium (226 + 228)
7% of 5,179 local samples were above the limit.
3
E. coli
5% of 145 local samples were above the limit.
4
Arsenic
3% of 5,807 local samples were above the limit.
5
Fluoride
<1% of 14,311 local samples were above the limit.
6
Lead
<1% of 5,732 local samples were above the limit.
7
Copper
<1% of 5,709 local samples were above the limit.
8
Volatile organic compounds (VOCs)
6,927 leaking underground storage tank sites on record locally.
9
Metals panel
977 hazardous waste sites on record locally.

Test your Iowa well for nitrate, radium (226 + 228) and E. coli

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

Free, one email

Send me the Iowa report

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

The rock under Iowa

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 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 Iowa

Iowa DNR records 6,927 leaking underground storage tank sites and 977 hazardous waste sites in Iowa, among 10,903 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.

6,927: leaking underground storage tank sitesGasoline and heating oil that leaked from tanks move through groundwater as benzene, MTBE and other volatile organic compounds.
977: hazardous waste sitesSolvents, degreasers and metals from industrial sites can travel far in fractured bedrock.
189: lined landfills and transfer facilities
1,334: other remediation projects
1,476: other solid waste facilities

Treatment that fits the local profile

Nitrate

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

Radium (226 + 228)

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

E. coli

Shock chlorination and fix the well cap or casing; UV disinfection whole-house; Chlorination system

Arsenic

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

Fluoride

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

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 E. coli

UV disinfection system

whole-house, at the point of entry, about $900

Fix the well cap and casing first; UV keeps bacteria from returning.

For E. coli

Aquasana Rhino Well Water with UV

whole-house, at the point of entry, about $2,871

Whole-house system built for wells: sediment pre-filter, KDF and carbon, and a UV lamp rated to kill 99.99% of bacteria and viruses. It does not remove arsenic, nitrate, uranium or radon.

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 lead

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 lead

Acid neutralizing filter

whole-house, at the point of entry, about $1,200

Raises pH so plumbing stops leaching lead and copper.

Common questions

Is there arsenic in well water in Iowa?

Arsenic was detected in 20% of 5,807 public well samples in Iowa, and 3% 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 Iowa?

The median radon level across 558 public samples in Iowa was 120 pCi/L, with a high of 2,290 pCi/L. New Hampshire recommends treatment above 2,000 pCi/L.

How often should I test a private well in Iowa?

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 Iowa

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

Sources

USGS Water Quality Portal: 110,251 samples in Iowa. 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 494,022 people on private wells in Iowa 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: 10,903 regulated sites located in Iowa. 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.