Your county health department
Wisconsin doesn't run a statewide free testing program that we know of. Some county health departments test wells or sell kits, so call yours first.
Wisconsin's private well pageArsenic in Wisconsin well water, by county
Arsenic has turned up often in 1 of the 7 Wisconsin counties with 10 or more tested wells, but those results likely overstate it, because of who tested the wells, when or where. 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 Wisconsin compares with the rest of the country
Across Wisconsin, about 1 in 20 tested wells had arsenic over the EPA limit of 10 µg/L (11 of 222). Across all tested wells in the US it's about 1 in 9. That's less often than in the country as a whole. Counties still differ, so check yours below.
Why it matters: Drinking it for years raises the risk of skin, bladder and lung cancer.
Arsenic dissolves out of certain rocks and old sediments, so it can be high even where nobody has polluted anything.
Arsenic in tested wells, county by county
Share of each county's tested wells with at least one result over the EPA limit of 10 µg/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 |
|---|---|---|---|
| Dane County | 19 | Widespread | |
| Shawano County | 13 | Worth checking | |
| Waupaca County | 15 | Worth checking | |
| Portage County | 32 | Rare | |
| Waukesha County | 18 | Rare | |
| Waushara County | 12 | Rare | |
| Marquette 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:
- Dane County: All of these tests come from the US Geological Survey in one small part of the county, so it may not match the rest of the county.
37 more Wisconsin counties have 1 to 9 tested wells for arsenic, too few to rate.
Download this table (CSV) · Free to reuse under CC BY 4.0
Where to get your well tested for arsenic in Wisconsin
A lab Wisconsin certifies
Ask for arsenic by name. Results from a certified lab count for a home sale or a loan.
Labs certified by WisconsinA mail-in kit
Fill the bottles at your kitchen tap and mail them back. We mark the kits that include arsenic.
Compare kitsKeep reading about wells in Wisconsin
- Well water testing in Wisconsin: how to get tested and what turns up statewide
- Arsenic in well water: where it comes from, what it does and how to remove it
- Nitrate in Wisconsin wells, by county
- Uranium in Wisconsin wells, by county
- Manganese in Wisconsin wells, by county
- Lead in Wisconsin wells, by county
Questions people ask about arsenic in Wisconsin
Is there arsenic in Wisconsin well water?
Arsenic has turned up often in 1 of the 7 Wisconsin counties with 10 or more tested wells, but those results likely overstate it, because of who tested the wells, when or where. Across Wisconsin, about 1 in 20 tested wells had arsenic over the EPA limit of 10 µg/L (11 of 222). Across all tested wells in the US it's about 1 in 9. 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 arsenic in Wisconsin?
Use a lab certified by Wisconsin for drinking water, or a mail-in kit that includes arsenic from a certified lab. Some county health departments test wells too, so call yours first.
See Wisconsin'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 limit of 10 µg/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 Natural Resources (DNR).