Arsenic in Wisconsin well water
In Wisconsin, 4% of 22,114 private wells tested between 1988 and 2025 had arsenic above the Wisconsin enforcement standard (10 ug/L), according to the UWSP Well Water Quality Viewer.
Arsenic occurs naturally in New England bedrock and dissolves into well water. Long-term exposure raises the risk of bladder, lung and skin cancers, and is linked to heart disease and lower IQ in children. It has no taste or smell, so testing is the only way to know.
Check your arsenic number
Type the value from your lab report. It is compared to the Wisconsin enforcement standard and the EPA limit, the same way the full interpretation does it.
Test your Wisconsin well for arsenic
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 $209Already tested? Upload the report
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.
Systems that remove arsenic
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.
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 arsenic
Under-sink reverse osmosis system
under-sink or countertop, about $300
Look for NSF/ANSI 58 certification listing the contaminant you need removed.
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 arsenic
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.
Rather have it installed and sized for your well? Book a free in-home water test with a licensed local company.
Where to get a well tested for arsenic in Wisconsin: certified labs, state programs and prices.
By county, from homeowner tests
Share of private wells above the state guidance level (10 ug/L) in tests homeowners sent to the state lab, 1989 to 2025.
| County | Above state level | Wells tested | Highest |
|---|---|---|---|
| Winnebago | 600 | 2,300 ug/L | |
| Outagamie | 403 | 4,300 ug/L | |
| Florence | 836 | 6,300 ug/L | |
| Shawano | 354 | 2,200 ug/L | |
| Marinette | 430 | 700 ug/L | |
| Ozaukee | 225 | 56 ug/L | |
| Menominee | 39 | 32 ug/L | |
| Dodge | 425 | 118 ug/L | |
| Walworth | 255 | 60.1 ug/L | |
| Lafayette | 118 | 74.8 ug/L | |
| Fond du Lac | 333 | 91 ug/L | |
| Jefferson | 1,178 | 94.8 ug/L | |
| Oconto | 434 | 129 ug/L | |
| Sheboygan | 220 | 36 ug/L | |
| Washington | 306 | 120 ug/L |
Towns with the highest share above the state level
- Center, Outagamie County45% of 67 wells
- Osborn, Outagamie County40% of 30 wells
- Algoma, Winnebago County39% of 147 wells
- Homestead, Florence County37% of 78 wells
- Niagara, Marinette County36% of 45 wells
- Morgan, Oconto County34% of 35 wells
- Emmet, Dodge County30% of 33 wells
- Cedarburg, Ozaukee County27% of 51 wells
- Matteson, Waupaca County27% of 30 wells
- Aurora, Florence County26% of 141 wells
- Angelica, Shawano County24% of 79 wells
- Clayton, Winnebago County22% of 101 wells
- Commonwealth, Florence County22% of 74 wells
- Watertown, Jefferson County20% of 70 wells
- Linn, Walworth County18% of 33 wells
- Fern, Florence County16% of 62 wells
- Milford, Jefferson County16% of 51 wells
- Norway, Racine County15% of 52 wells
- Ixonia, Jefferson County14% of 111 wells
- Farmington, Jefferson County14% of 63 wells
- Neenah, Winnebago County12% of 34 wells
- Winneconne, Winnebago County11% of 53 wells
- Hobart village, Brown County10% of 67 wells
- Tipler, Florence County10% of 58 wells
- Menominee, Menominee County10% of 39 wells
By county, from individual samples
Public monitoring samples against the EPA limit (10 ug/L); counties with at least 30 samples.
Sources
- Wisconsin Well Water Quality Viewer samples: Private well samples compiled by the UWSP Center for Watershed Science and Education from the DNR Groundwater Retrieval Network, DATCP surveys, the UWSP Water and Environmental Analysis Lab and county health programs, published in the Wisconsin Well Water Quality Viewer with Wisconsin DHS. Samples are located to the town, village or city they fall in; one result per well and parameter (the latest) so repeat samples do not double count; wells without a state well number are keyed by location. Shares are against Wisconsin NR 140 enforcement standards (arsenic 10 ug/L, nitrate 10 mg/L as N, manganese 300 ug/L, lead 15 ug/L, copper 1.3 mg/L) and the iron and chloride secondary levels. Many samples were submitted by homeowners with a reason to test, so shares can run above a random survey. Retrieved September 9, 2026.
- Individual samples from the USGS Water Quality Portal and state monitoring, summarized per geography. arsenic counts and shares are listed on each county and town page with their sources.
Analysis: Arsenic in private wells, state by state, from the same public records.