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Is Lake Wisconsin, WI tap water safe?

4 utilities serve Lake Wisconsin, 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 4 utilities serving Lake Wisconsin have a result above a legal limit or action level, or a health-based violation since 2016, in EPA’s and Wisconsin’s records: Lodi Waterworks, Prairie Du Sac Waterworks and Poynette Waterworks.

Lodi Waterworks, which serves the most people here, has 1 result above the action level and 1 result above the health goal. The worst: Lead at 18 ppb, above the action level.

The water from Lodi Waterworks is very hard, typically 308 mg/L (18 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 Lake Wisconsin’s ZIP codes, from EPA’s estimates.

What handles it

Each of these is certified, on a certifier’s listing, for a result above a line in Lodi Waterworks’s water, which serves the most people here. Another utility’s report names what handles its own results.

Disclosure: TapBuff earns a commission if you buy through some links on this page. It does not change which standard or filter we name. As an Amazon Associate, TapBuff earns from qualifying purchases. How TapBuff makes money

Every claim, and more filters, in the full report

Water testing near Lake Wisconsin

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 Lake Wisconsin, in a straight line. Call first: certification is test by test, and not every lab takes samples from homeowners.

  • CT Laboratories

    Baraboo, WI · about 11 miles

    Certified for bacteria, nitrate, lead and copper, metals, minerals and other inorganics, organic chemicals, disinfection byproducts

    (608) 356-2760

  • Public Health Madison & Dane County

    Madison, WI · about 22 miles

    Certified for bacteria

    (608) 243-0357

  • Wisconsin State Laboratory of Hygiene

    Madison, WI · about 23 miles

    Certified for bacteria, nitrate, lead and copper, metals, minerals and other inorganics, organic chemicals, disinfection byproducts, PFAS, radioactivity

    (608) 224-6260

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 Lake Wisconsin

Which ZIP codes are in Lake Wisconsin: 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 Lake Wisconsin

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

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