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privatewelldata / States / Wisconsin

Wisconsin well water testing

Wisconsin keeps an official list of certified drinking-water labs; 3% of 548 sampled wells were above the arsenic limit across 69 counties. Updated 2026-10-17.

Official lab list for Wisconsin

Wisconsin State Laboratory of Hygiene – water test pricesWisconsin's state lab posts its current fees for homeowner well tests, from single tests to full packages.www.slh.wisc.edu · checked 2026-10-18

Coverage map

Map of Wisconsin: 0 listed labs open to private wells shown as dots, and 69 counties shaded by the share of sampled wells above the arsenic limit.
Counties shaded by share of sampled wells above 10 µg/L arsenic: 0 1–5% 5–10% 10–25% 25–50% 50%+ grey = no data. Sources: official state list; USGS/EPA Water Quality Portal; US Census boundaries · privatewelldata.com

Well water results by county

69 rows · showing 1–25

Share of sampled wells above the EPA limit. Source: USGS/EPA Water Quality Portal · privatewelldata.com
CountyArsenic > 10 µg/LNitrate > 10 mg/L
Adams County0% of 104% of 27
Ashland County0% of 450% of 79
Barron County–6% of 53
Bayfield County–0% of 77
Brown County2% of 451% of 103
Buffalo County–0% of 12
Burnett County0% of 270% of 58
Calumet County–4% of 27
Chippewa County–3% of 31
Clark County–0% of 29
Columbia County–5% of 115
Crawford County–12% of 33
Dane County16% of 258% of 131
Dodge County0% of 102% of 108
Door County–0% of 38
Douglas County–0% of 94
Dunn County–9% of 43
Eau Claire County–0% of 31
Florence County–0% of 18
Fond du Lac County–4% of 45
Forest County2% of 514% of 100
Grant County0% of 136% of 50
Green County–7% of 27
Green Lake County–20% of 10
Iowa County0% of 1211% of 36
Jackson County–0% of 14
Jefferson County–0% of 80
Juneau County–7% of 15
Kenosha County0% of 120% of 29
Kewaunee County–0% of 16
La Crosse County–6% of 51
Lafayette County–6% of 32
Langlade County0% of 180% of 64
Lincoln County–0% of 22
Manitowoc County–2% of 54
Marathon County–31% of 13
Marinette County14% of 140% of 34
Marquette County0% of 1116% of 19
Menominee County3% of 361% of 70
Milwaukee County–0% of 78
Monroe County–11% of 19
Oconto County0% of 100% of 20
Oneida County–0% of 14
Outagamie County–0% of 12
Ozaukee County–0% of 66
Pepin County–20% of 10
Pierce County–3% of 29
Polk County0% of 120% of 55
Price County–8% of 13
Racine County8% of 130% of 38
Richland County–0% of 16
Rock County–12% of 58
Rusk County–0% of 21
Sauk County–3% of 33
Sawyer County–0% of 22
Shawano County4% of 468% of 92
Sheboygan County–4% of 69
St. Croix County–4% of 113
Trempealeau County–0% of 28
Vernon County–0% of 36
Vilas County0% of 563% of 120
Walworth County20% of 151% of 109
Washburn County–0% of 21
Washington County–1% of 123
Waukesha County0% of 311% of 195
Waupaca County6% of 1715% of 20
Waushara County0% of 1914% of 29
Winnebago County–8% of 12
Wood County–3% of 165

Nitrate: 3% of 3,524 sampled wells statewide. All Wisconsin counties →

How to choose a lab

  1. Pick a lab on the official list above that is certified for each test you need (bacteria and chemistry are often separate certifications).
  2. Ask for the lab’s own sample bottles and instructions; bacteria samples usually must reach the lab within 24–30 hours.
  3. Compare prices for a basic package (bacteria, nitrate, pH/TDS) and add arsenic or other metals where local data shows a risk.
  4. Be wary of free in-home tests from treatment-system sellers — see our salesperson checklist.

Based on CDC and EPA private-well guidance.

Questions

Where can I get my well water tested in Wisconsin?

Use the official certified-lab list linked on this page; call the lab to confirm it accepts private well samples and is certified for the tests you need.

What should I test my well for in Wisconsin?

Test every year for bacteria (total coliform and E. coli), nitrate, pH and total dissolved solids (CDC). In Wisconsin, 3% of sampled wells with arsenic data were above the EPA limit, so include arsenic. Use our test helper for a list that fits your home.

Is there well water data for my county in Wisconsin?

Yes for 69 counties: we show the share of sampled wells above the EPA arsenic and nitrate limits, from the Water Quality Portal (USGS/EPA). These are monitoring wells as well as private wells, so test your own well.

Get a test list for your home → · If a result is high