Sodium in Wisconsin well water
In Wisconsin, 11% of 6,432 private wells tested between 1999 and 2025 had sodium above the EPA advisory level (20 mg/L), according to the UWSP Well Water Quality Viewer.
Sodium enters wells with road salt and from softeners. EPA's guidance level of 20 mg/L matters for people on sodium-restricted diets; most people are not affected below 250 mg/L.
Check your sodium number
Type the value from your lab report. It is compared to the EPA advisory level and the EPA limit, the same way the full interpretation does it.
Test your Wisconsin well for sodium
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 sodium
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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 sodium
Under-sink reverse osmosis system
under-sink or countertop, about $300
Look for NSF/ANSI 58 certification listing the contaminant you need removed.
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 sodium in Wisconsin: certified labs, state programs and prices.
By county, from homeowner tests
Share of private wells above the state guidance level (20 mg/L) in tests homeowners sent to the state lab, 1999 to 2025.
| County | Above state level | Wells tested | Highest |
|---|---|---|---|
| Sheboygan | 71 | 68.3 mg/L | |
| Calumet | 122 | 547 mg/L | |
| Douglas | 122 | 1,022 mg/L | |
| Fond du Lac | 122 | 461 mg/L | |
| Washington | 36 | 259 mg/L | |
| Dodge | 123 | 183 mg/L | |
| Jefferson | 746 | 259 mg/L | |
| Shawano | 33 | 147 mg/L | |
| Waupaca | 83 | 149 mg/L | |
| Wood | 39 | 256 mg/L | |
| Kewaunee | 45 | 205 mg/L | |
| Green | 210 | 91.0 mg/L | |
| Green Lake | 78 | 65.2 mg/L | |
| Portage | 219 | 162 mg/L | |
| Brown | 70 | 167 mg/L |
Towns with the highest share above the state level
- Chilton, Calumet County45% of 33 wells
- Oakland, Jefferson County43% of 67 wells
- Koshkonong, Jefferson County41% of 74 wells
- Aztalan, Jefferson County38% of 40 wells
- Sullivan, Jefferson County28% of 47 wells
- Ixonia, Jefferson County24% of 76 wells
- Knowlton, Marathon County22% of 50 wells
- Hull, Portage County21% of 39 wells
- Lafayette, Chippewa County19% of 42 wells
- New Glarus, Green County18% of 44 wells
- Merrimac, Sauk County16% of 31 wells
- Mosinee, Marathon County15% of 33 wells
- Jefferson, Jefferson County15% of 40 wells
- Farmington, Jefferson County15% of 47 wells
- Concord, Jefferson County15% of 48 wells
- Lake Mills, Jefferson County14% of 57 wells
- Hebron, Jefferson County11% of 35 wells
- Waterloo, Jefferson County9% of 47 wells
- Eagle Point, Chippewa County8% of 50 wells
- Watertown, Jefferson County7% of 41 wells
- Tilden, Chippewa County6% of 31 wells
- St. Joseph, St. Croix County3% of 31 wells
- Anson, Chippewa County3% of 31 wells
- Palmyra, Jefferson County3% of 32 wells
- Stockton, Portage County3% of 33 wells
By county, from individual samples
Public monitoring samples against the EPA limit; counties with at least 30 samples.
| County | Above EPA limit | Samples | Detected | Median | Highest |
|---|---|---|---|---|---|
| Ashland | no limit | 56 | 100% | 24 | 2,480 mg/L |
| Adams | no limit | 172 | 100% | 1.4 | 22.1 mg/L |
| Bayfield | no limit | 536 | 100% | 1.1 | 98 mg/L |
| Brown | no limit | 203 | 100% | 24 | 500 mg/L |
| Burnett | no limit | 34 | 100% | 2.95 | 49 mg/L |
| Barron | no limit | 55 | 100% | 3.5 | 14 mg/L |
| Chippewa | no limit | 35 | 100% | 3.3 | 7.8 mg/L |
| Columbia | no limit | 148 | 100% | 3 | 120 mg/L |
| Crawford | no limit | 38 | 100% | 2.65 | 840 mg/L |
| Dane | no limit | 150 | 100% | 3.5 | 320 mg/L |
| Dodge | no limit | 129 | 100% | 6.7 | 52 mg/L |
| Door | no limit | 36 | 100% | 6.9 | 620 mg/L |
| Calumet | no limit | 39 | 100% | 17 | 890 mg/L |
| Dunn | no limit | 37 | 100% | 2.8 | 20 mg/L |
| Eau Claire | no limit | 40 | 100% | 2.1 | 53 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. sodium counts and shares are listed on each county and town page with their sources.