Lead in Wisconsin well water

In Wisconsin, 3% of 7,937 private wells tested between 1994 and 2025 had lead above the Wisconsin enforcement standard (15 ug/L), according to the UWSP Well Water Quality Viewer.

Lead in well water almost always comes from household plumbing and older fixtures, not the aquifer, and corrosive (low pH) well water makes it worse. There is no safe level for children; it harms brain development.

Check your lead 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 lead

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 $209 Already 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 lead

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 lead

Under-sink reverse osmosis system

under-sink or countertop, about $300

Look for NSF/ANSI 58 certification listing the contaminant you need removed.

For lead

Acid neutralizing filter

whole-house, at the point of entry, about $1,200

Raises pH so plumbing stops leaching lead and copper.

For lead

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 lead in Wisconsin: certified labs, state programs and prices.

By county, from homeowner tests

Share of private wells above the state guidance level (15 ug/L) in tests homeowners sent to the state lab, 2018 to 2025.

County	Above state level	Wells tested	Highest
Pepin	9%	97	1,436 ug/L
Oneida	8%	102	65 ug/L
Oconto	6%	35	77 ug/L
Washington	5%	73	49 ug/L
Clark	5%	74	33 ug/L
Lincoln	5%	37	17 ug/L
Juneau	5%	64	102 ug/L
Calumet	4%	226	2,529 ug/L
Chippewa	4%	545	789 ug/L
Douglas	4%	161	67 ug/L
Fond du Lac	3%	174	125 ug/L
Monroe	3%	30	22 ug/L
Marathon	3%	816	541 ug/L
Washburn	3%	31	19 ug/L
Wood	3%	67	30 ug/L

Towns with the highest share above the state level

Troy, St. Croix County10% of 31 wells
Stettin, Marathon County8% of 36 wells
Excelsior, Sauk County6% of 31 wells
Mosinee, Marathon County6% of 48 wells
Anson, Chippewa County6% of 34 wells
Tilden, Chippewa County6% of 34 wells
Eagle Point, Chippewa County6% of 52 wells
Palmyra, Jefferson County5% of 40 wells
Knowlton, Marathon County5% of 63 wells
Koshkonong, Jefferson County5% of 86 wells
Lafayette, Chippewa County4% of 45 wells
Aztalan, Jefferson County4% of 47 wells
Ixonia, Jefferson County3% of 90 wells
Woodmohr, Chippewa County3% of 30 wells
Milford, Jefferson County3% of 36 wells
Hebron, Jefferson County3% of 36 wells
Hudson, St. Croix County3% of 36 wells
Stockton, Portage County3% of 40 wells
Merrimac, Sauk County2% of 42 wells
Caledonia, Columbia County2% of 44 wells
Jefferson, Jefferson County2% of 44 wells
Stockbridge, Calumet County2% of 45 wells
Watertown, Jefferson County2% of 49 wells
Wheaton, Chippewa County2% of 49 wells
Chilton, Calumet County2% of 51 wells

By county, from individual samples

Public monitoring samples against the EPA limit (15 ug/L); counties with at least 30 samples.

County	Above EPA limit	Samples	Detected	Median	Highest
Ashland	26%	50	76%	6.5	1,000 ug/L
Menominee	11%	46	76%	0	26 ug/L
Shawano	4%	68	25%	0	200 ug/L
Vilas	2%	62	81%	0	16,200 ug/L
Brown	2%	65	66%	0	21 ug/L
Portage	0%	138	71%	0	0.98 ug/L
Forest	0%	64	50%	0	0.23 ug/L
Waukesha	0%	56	45%	0	0.421 ug/L
Waupaca	0%	37	43%	0	0.225 ug/L
Marquette	0%	30	37%	0	1.27 ug/L
Waushara	0%	30	37%	0	0.406 ug/L
Douglas	0%	299	3%	0	0 ug/L
Bayfield	0%	290	2%	0	0.066 ug/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. lead counts and shares are listed on each county and town page with their sources.