Copper in Wisconsin well water
In Wisconsin, 1% of 7,890 private wells tested between 1996 and 2025 had copper above the Wisconsin enforcement standard (1.3 mg/L), according to the UWSP Well Water Quality Viewer.
Copper leaches from pipes when water is acidic. Above 1.3 mg/L it causes stomach upset, and long-term exposure can harm the liver and kidneys. Blue-green stains on fixtures are the giveaway.
Check your copper 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 copper
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
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Systems that remove copper
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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 copper
Under-sink reverse osmosis system
under-sink or countertop, about $300
Look for NSF/ANSI 58 certification listing the contaminant you need removed.
For copper
Acid neutralizing filter
whole-house, at the point of entry, about $1,200
Raises pH so plumbing stops leaching lead and copper.
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 copper in Wisconsin: certified labs, state programs and prices.
By county, from homeowner tests
Share of private wells above the state guidance level (1.3 mg/L) in tests homeowners sent to the state lab, 2005 to 2025.
| County | Above state level | Wells tested | Highest |
|---|---|---|---|
| Lincoln | 37 | 2.84 mg/L | |
| Trempealeau | 74 | 2.8 mg/L | |
| Washburn | 31 | 1.41 mg/L | |
| Sauk | 347 | 15.9 mg/L | |
| Clark | 71 | 6.5 mg/L | |
| Manitowoc | 61 | 5.32 mg/L | |
| Kewaunee | 58 | 4.66 mg/L | |
| Lafayette | 30 | 2.96 mg/L | |
| Door | 167 | 3.17 mg/L | |
| Oneida | 103 | 1.74 mg/L | |
| Calumet | 226 | 3.98 mg/L | |
| St. Croix | 270 | 2.52 mg/L | |
| Vilas | 78 | 2.42 mg/L | |
| Crawford | 39 | 1.5 mg/L | |
| Langlade | 40 | 1.66 mg/L |
Towns with the highest share above the state level
- Excelsior, Sauk County9% of 32 wells
- Stockbridge, Calumet County7% of 45 wells
- Troy, St. Croix County6% of 31 wells
- Wheaton, Chippewa County4% of 49 wells
- Harrison village, Calumet County3% of 30 wells
- Tilden, Chippewa County3% of 34 wells
- Cooks Valley, Chippewa County3% of 40 wells
- Lafayette, Chippewa County2% of 45 wells
- Dekorra, Columbia County2% of 47 wells
- Waterloo, Jefferson County2% of 49 wells
- Koshkonong, Jefferson County1% of 86 wells
- Ixonia, Jefferson County1% of 90 wells
- Oakland, Jefferson County0% of 78 wells
- Lake Mills, Jefferson County0% of 65 wells
- Knowlton, Marathon County0% of 63 wells
- Sullivan, Jefferson County0% of 54 wells
- Concord, Jefferson County0% of 54 wells
- New Glarus, Green County0% of 54 wells
- Farmington, Jefferson County0% of 53 wells
- Hull, Portage County0% of 52 wells
- Eagle Point, Chippewa County0% of 52 wells
- Chilton, Calumet County0% of 51 wells
- Watertown, Jefferson County0% of 49 wells
- Mosinee, Marathon County0% of 48 wells
- Aztalan, Jefferson County0% of 47 wells
By county, from individual samples
Public monitoring samples against the EPA limit (1.3 mg/L); counties with at least 30 samples.
| County | Above EPA limit | Samples | Detected | Median | Highest |
|---|---|---|---|---|---|
| Vilas | 61 | 82% | 0 | 1.5 mg/L | |
| Ashland | 47 | 98% | 0.007 | 0.14 mg/L | |
| Marquette | 30 | 87% | 0.001 | 0.03 mg/L | |
| Menominee | 46 | 76% | 0.004 | 0.23 mg/L | |
| Waupaca | 35 | 74% | 0.001 | 0.014 mg/L | |
| Shawano | 60 | 72% | 0.006 | 0.44 mg/L | |
| Brown | 38 | 71% | 0.002 | 0.077 mg/L | |
| Portage | 86 | 71% | 0 | 0.755 mg/L | |
| Forest | 65 | 69% | 0 | 0.52 mg/L | |
| Waukesha | 58 | 69% | 0.001 | 0.035 mg/L | |
| Bayfield | 344 | 10% | 0 | 0.02 mg/L | |
| Douglas | 354 | 8% | 0 | 0.05 mg/L |
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. copper counts and shares are listed on each county and town page with their sources.