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Manganese in Idaho 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 6 of the 44 Idaho 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 Idaho compares with the rest of the country

Across Idaho, about 1 in 11 tested wells had manganese over the EPA health advisory of 0.3 mg/L (239 of 2,543). Across all tested wells in the US it's about 1 in 7. That's less often than in the country as a whole. Counties still differ, so check yours 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
Shoshone County 339
38% 129 of 339
 Widespread
Camas County 11
36% 4 of 11
 Widespread
Owyhee County 56
20% 11 of 56
 Widespread
Washington County 36
19% 7 of 36
 Widespread
Valley County 21
19% 4 of 21
 Widespread
Boise County 20
15% 3 of 20
 Widespread
Caribou County 113
14% 16 of 113
 Worth checking
Bear Lake County 22
14% 3 of 22
 Worth checking
Oneida County 22
14% 3 of 22
 Worth checking
Adams County 15
13% 2 of 15
 Worth checking
Gem County 64
9% 6 of 64
 Worth checking
Butte County 144
9% 13 of 144
 Worth checking
Bannock County 56
7% 4 of 56
 Worth checking
Bonner County 57
7% 4 of 57
 Worth checking
Payette County 32
6% 2 of 32
 Worth checking
Canyon County 161
5% 8 of 161
 Rare
Fremont County 43
5% 2 of 43
 Rare
Kootenai County 44
5% 2 of 44
 Rare
Elmore County 87
3% 3 of 87
 Rare
Jefferson County 62
3% 2 of 62
 Rare
Ada County 162
3% 5 of 162
 Rare
Benewah County 36
3% 1 of 36
 Rare
Latah County 37
3% 1 of 37
 Rare
Minidoka County 81
2% 2 of 81
 Rare
Cassia County 60
2% 1 of 60
 Rare
Twin Falls County 104
1% 1 of 104
 Rare
Bingham County 86
0% 0 of 86
 Rare
Jerome County 82
0% 0 of 82
 Rare
Blaine County 70
0% 0 of 70
 Rare
Gooding County 58
0% 0 of 58
 Rare
Power County 42
0% 0 of 42
 Rare
Lincoln County 40
0% 0 of 40
 Rare
Idaho County 36
0% 0 of 36
 Rare
Bonneville County 34
0% 0 of 34
 Rare
Custer County 32
0% 0 of 32
 Rare
Clark County 28
0% 0 of 28
 Rare
Nez Perce County 28
0% 0 of 28
 Rare
Lemhi County 24
0% 0 of 24
 Rare
Madison County 23
0% 0 of 23
 Rare
Boundary County 17
0% 0 of 17
 Rare
Lewis County 17
0% 0 of 17
 Rare
Teton County 15
0% 0 of 15
 Rare
Clearwater County 13
0% 0 of 13
 Rare
Franklin County 13
0% 0 of 13
 Rare

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Where to get your well tested for manganese in Idaho

1

Free state testing

Idaho sends well owners a free test kit, one per household every 5 years. Check which tests it includes before you count on it for manganese.

Idaho's private well page
2

A lab Idaho certifies

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

Labs certified by Idaho
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 Idaho

Questions people ask about manganese in Idaho

Is there manganese in Idaho well water?

Manganese is widespread, over the limit in 15% or more of tested wells, in 6 of the 44 Idaho counties with 10 or more tested wells. Across Idaho, about 1 in 11 tested wells had manganese over the EPA health advisory of 0.3 mg/L (239 of 2,543). Across all tested wells in the US it's about 1 in 7. That's less often than in the country as a whole. Counties still differ, so check yours below.

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

Idaho sends well owners a free test kit, one per household every 5 years. If that doesn't cover you, use a lab certified by Idaho for drinking water, or a mail-in kit that includes manganese from a certified lab.

See Idaho'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: Department of Health and Welfare.