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Manganese in Iowa well water, by county

By the Tested Water teamLab data from the USGS and EPA Water Quality Portal, 2000 to 2023Updated November 8, 2026

Manganese is widespread, over the limit in 15% or more of tested wells, in 36 of the 68 Iowa counties with 10 or more tested wells. A county's share tells you how likely a problem is nearby. Only a test of your own well tells you what's in it.

Find a manganese test See every county

How Iowa compares with the rest of the country

Across Iowa, about 2 in 10 tested wells had manganese over the EPA health advisory of 0.3 mg/L (343 of 1,535). Across all tested wells in the US it's about 1 in 7. So manganese turns up somewhat more often in Iowa than in the country as a whole. Check your county below.

Why it matters: High levels over many years may affect the nervous system, and babies are more sensitive to it. It also leaves black stains.

Manganese dissolves out of rock and soil, especially in water with little oxygen.

Manganese in tested wells, county by county

Share of each county's tested wells with at least one result over the EPA health advisory of 0.3 mg/L. Counties need 10 or more tested wells to be listed. Widespread means 15% or more, worth checking 5 to 15%, rare under 5%.

CountyWells testedWells over the limitLevel
O'Brien County 18
78% 14 of 18
 Widespread
Audubon County 16
75% 12 of 16
 Widespread
Emmet County 11
55% 6 of 11
 Widespread
Shelby County 13
54% 7 of 13
 Widespread
Sac County 17
53% 9 of 17
 Widespread
Sioux County 24
50% 12 of 24
 Widespread
Lyon County 12
50% 6 of 12
 Widespread
Harrison County 19
47% 9 of 19
 Widespread
Humboldt County 15
47% 7 of 15
 Widespread
Hamilton County 63
43% 27 of 63
 Widespread
Crawford County 15
40% 6 of 15
 Widespread
Carroll County 31
39% 12 of 31
 Widespread
Monona County 21
38% 8 of 21
 Widespread
Linn County 74
38% 28 of 74
 Widespread
Wright County 16
38% 6 of 16
 Widespread
Pottawattamie County 25
36% 9 of 25
 Widespread
Polk County 14
36% 5 of 14
 Widespread
Cherokee County 27
33% 9 of 27
 Widespread
Dubuque County 18
33% 6 of 18
 Widespread
Cass County 15
33% 5 of 15
 Widespread
Dallas County 46
33% 15 of 46
 Widespread
Guthrie County 19
32% 6 of 19
 Widespread
Montgomery County 13
31% 4 of 13
 Widespread
Page County 10
30% 3 of 10
 Widespread
Hardin County 57
30% 17 of 57
 Widespread
Plymouth County 21
29% 6 of 21
 Widespread
Franklin County 11
27% 3 of 11
 Widespread
Mills County 23
26% 6 of 23
 Widespread
Jasper County 39
26% 10 of 39
 Widespread
Kossuth County 12
25% 3 of 12
 Widespread
Marion County 12
25% 3 of 12
 Widespread
Palo Alto County 16
19% 3 of 16
 Widespread
Johnson County 22
18% 4 of 22
 Widespread
Ida County 11
18% 2 of 11
 Widespread
Hancock County 17
18% 3 of 17
 Widespread
Marshall County 19
16% 3 of 19
 Widespread
Story County 27
15% 4 of 27
 Worth checking
Tama County 22
14% 3 of 22
 Worth checking
Muscatine County 30
13% 4 of 30
 Worth checking
Woodbury County 37
11% 4 of 37
 Worth checking
Benton County 29
10% 3 of 29
 Worth checking
Buena Vista County 21
10% 2 of 21
 Worth checking
Iowa County 15
7% 1 of 15
 Worth checking
Louisa County 18
6% 1 of 18
 Worth checking
Buchanan County 19
5% 1 of 19
 Worth checking
Clinton County 23
4% 1 of 23
 Rare
Webster County 31
0% 0 of 31
 Rare
Butler County 25
0% 0 of 25
 Rare
Winneshiek County 25
0% 0 of 25
 Rare
Clayton County 24
0% 0 of 24
 Rare
Black Hawk County 23
0% 0 of 23
 Rare
Jackson County 23
0% 0 of 23
 Rare
Scott County 17
0% 0 of 17
 Rare
Fayette County 16
0% 0 of 16
 Rare
Washington County 16
0% 0 of 16
 Rare
Fremont County 15
0% 0 of 15
 Rare
Keokuk County 15
0% 0 of 15
 Rare
Floyd County 13
0% 0 of 13
 Rare
Grundy County 13
0% 0 of 13
 Rare
Mitchell County 13
0% 0 of 13
 Rare
Chickasaw County 12
0% 0 of 12
 Rare
Greene County 12
0% 0 of 12
 Rare
Allamakee County 11
0% 0 of 11
 Rare
Boone County 11
0% 0 of 11
 Rare
Delaware County 11
0% 0 of 11
 Rare
Howard County 11
0% 0 of 11
 Rare
Worth County 11
0% 0 of 11
 Rare
Jones County 10
0% 0 of 10
 Rare

21 more Iowa counties have 1 to 9 tested wells for manganese, too few to rate.

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Where to get your well tested for manganese in Iowa

1

Free state testing

Iowa tests private wells for bacteria, nitrate, arsenic and manganese for free through participating county health offices. Check which tests it includes before you count on it for manganese.

Iowa's private well page
2

A lab Iowa certifies

Ask for manganese by name. Results from a certified lab count for a home sale or a loan.

Labs certified by Iowa
3

A mail-in kit

Fill the bottles at your kitchen tap and mail them back. We mark the kits that include manganese.

Compare kits

Keep reading about wells in Iowa

Questions people ask about manganese in Iowa

Is there manganese in Iowa well water?

Manganese is widespread, over the limit in 15% or more of tested wells, in 36 of the 68 Iowa counties with 10 or more tested wells. Across Iowa, about 2 in 10 tested wells had manganese over the EPA health advisory of 0.3 mg/L (343 of 1,535). Across all tested wells in the US it's about 1 in 7. So manganese turns up somewhat more often in Iowa than in the country as a whole. Check your county below.

Where can I get my well tested for manganese in Iowa?

Iowa tests private wells for bacteria, nitrate, arsenic and manganese for free through participating county health offices. If that doesn't cover you, use a lab certified by Iowa for drinking water, or a mail-in kit that includes manganese from a certified lab.

See Iowa's list of certified labs, or compare mail-in kits.

Where these numbers come from

  • Lab tests: Water Quality Portal (USGS and EPA), well samples since 2000. A well counts as over if any of its tests was over the EPA health advisory of 0.3 mg/L. Wells tested for studies and monitoring, not a random sample of homes.
  • Likely overstated: our own check of who tested the wells, when and where. How we check.
  • State programs and links: Iowa Department of Natural Resources.