Free testing, with limits
Free nitrate and bacteria testing in Washington is limited to parts of the Lower Yakima Valley and western Benton County. Check which tests it includes before you count on it for manganese.
Washington's private well pageManganese in Washington well water, by county
Manganese is widespread, over the limit in 15% or more of tested wells, in 4 of the 17 Washington counties with 10 or more tested wells. 1 more look high, but those results likely overstate it. 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.
How Washington compares with the rest of the country
Across Washington, about 2 in 10 tested wells had manganese over the EPA health advisory of 0.3 mg/L (112 of 717). Across all tested wells in the US it's about 1 in 7. Washington is about average, so the county you live in tells you more than the state does.
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%.
| County | Wells tested | Wells over the limit | Level |
|---|---|---|---|
| Stevens County | 116 | Widespread | |
| Kitsap County | 81 | Widespread | |
| Ferry County | 10 | Widespread | |
| Whatcom County | 68 | Widespread | |
| Clark County | 21 | Widespread | |
| Thurston County | 99 | Worth checking | |
| Okanogan County | 44 | Worth checking | |
| Yakima County | 36 | Rare | |
| Pierce County | 58 | Rare | |
| Grant County | 38 | Rare | |
| Franklin County | 28 | Rare | |
| Spokane County | 24 | Rare | |
| Kittitas County | 20 | Rare | |
| Mason County | 17 | Rare | |
| Douglas County | 11 | Rare | |
| Whitman County | 11 | Rare | |
| Adams County | 10 | Rare |
* Likely overstated. These shares come from a narrow set of wells, so they probably run high for the county as a whole:
- Clark County: All of these tests come from a single agency between 2003 and 2005 in one small part of the county, so this likely overstates it.
10 more Washington 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 Washington
A lab Washington certifies
Ask for manganese by name. Results from a certified lab count for a home sale or a loan.
Labs certified by WashingtonA mail-in kit
Fill the bottles at your kitchen tap and mail them back. We mark the kits that include manganese.
Compare kitsKeep reading about wells in Washington
- Well water testing in Washington: how to get tested and what turns up statewide
- Manganese in well water: where it comes from, what it does and how to remove it
- Nitrate in Washington wells, by county
- Arsenic in Washington wells, by county
- Uranium in Washington wells, by county
- Lead in Washington wells, by county
- Radon in Washington wells, by county
Questions people ask about manganese in Washington
Is there manganese in Washington well water?
Manganese is widespread, over the limit in 15% or more of tested wells, in 4 of the 17 Washington counties with 10 or more tested wells. 1 more look high, but those results likely overstate it. Across Washington, about 2 in 10 tested wells had manganese over the EPA health advisory of 0.3 mg/L (112 of 717). Across all tested wells in the US it's about 1 in 7. Washington is about average, so the county you live in tells you more than the state does.
Where can I get my well tested for manganese in Washington?
Free nitrate and bacteria testing in Washington is limited to parts of the Lower Yakima Valley and western Benton County. If that doesn't cover you, use a lab certified by Washington for drinking water, or a mail-in kit that includes manganese from a certified lab.
See Washington'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 (DOH); Department of Ecology for well records and lab accreditation.