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Is Potosi, WI tap water safe?

3 utilities serve Potosi, by EPA’s records. Here is what EPA’s and Wisconsin’s records show for each, against the legal limits and the stricter health goals.

Matched to your utility using EPA records.

The short answer

3 of the 3 utilities serving Potosi have a result above a legal limit or action level, or a health-based violation since 2016, in EPA’s and Wisconsin’s records: Tennyson Waterworks, Potosi Waterworks and River Vista Estates LLC.

Tennyson Waterworks, which serves the most people here, has 1 result above the health goal. The worst: Uranium at 0.26 ppb, above the health goal. Health goals are stricter than legal limits and are not enforced.

The water from Tennyson Waterworks is very hard, 318 mg/L (18.6 grains per gallon). How Wisconsin’s water compares.

A town can be served by more than one utility, and some homes are on private wells. The name on your water bill tells you which is yours, and your ZIP code narrows it down. They are listed by how many people each serves in Potosi’s ZIP codes, from EPA’s estimates.

Water testing near Potosi

A utility tests the water it sends out. A test of your own tap shows what your pipes add, and on a private well it is the only test there is. It takes a lab Wisconsin certifies.

The 3 labs Wisconsin certifies closest to Potosi, in a straight line. Call first: certification is test by test, and not every lab takes samples from homeowners.

  • LV Labs WW, LLC

    Lancaster, WI · about 10 miles

    Certified for bacteria, nitrate

    (608) 723-4096

  • Lafayette County Health Department

    Darlington, WI · about 30 miles

    Certified for bacteria, nitrate

    (608) 776-4895

  • Iowa County

    Dodgeville, WI · about 34 miles

    Certified for bacteria

    (608) 930-9870

Wisconsin State Laboratory of Hygiene: Well water test kits ordered by phone and shipped free; you pay to mail the sample back, and the lab bills you after testing. Tests run from bacteria alone to a homeowner package covering bacteria, nitrate, fluoride, metals, hardness, volatile organic compounds and atrazine. Bacteria is $35, nitrate $35, lead $38, and the homeowner package $450, as of July 1, 2026. Public Environmental and Water Testing Prices, Wisconsin State Laboratory of Hygiene.

All 156 certified labs for Wisconsin

ZIP codes in Potosi

Which ZIP codes are in Potosi: Census 2020 relationship files. Which utilities serve them, and how many people: EPA SDWIS and EPA’s service area map. Each utility’s results: EPA UCMR 5, EPA SDWIS, and EPA’s and the state’s compliance monitoring, as its report lists them. How they are measured: methodology. Certified labs: Wisconsin DNR and DATCP, certified and approved drinking water laboratories; distances from the Census 2020 ZIP code tabulation area gazetteer.

Near Potosi

Other towns in Grant County with a page of their own.

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