Wilton Waterworks
What EPA’s and Wisconsin’s records show in this utility’s water: nitrate, arsenic and other regulated chemicals; lead and copper; and violations since 2016, with the certification that handles each result.
- Serves
- 490 people
- Connections
- 263
- Water source
- Groundwater
- Based in
- Wilton, WI
- County
- Monroe
- Owner
- Local government
- Hardness
- Hard
The ZIP code it serves
The short answer
1 result is above the health goal. The worst: Uranium, above the health goal. 2 health-based violations since 2016.
What handles itWhat was found
Total trihalomethanes (TTHM), haloacetic acids (HAA5), fluoride, nitrate, arsenic and chromium (total): Wisconsin’s own results, samples taken from April 14, 2020 to Sept. 15, 2026, with EPA’s 2012 to 2019 file for earlier years.
Uranium: EPA’s compliance monitoring file, samples taken from March 16, 2017 to March 16, 2017. Newer results are in the utility’s annual water quality report.
Above the health goal1
Uranium
Comes from the source
0.035ppb
Highest yearly average, 2017
Averaged by year, the highest was 0.035 ppb, in 2017: below EPA’s legal limit of 30 ppb, but above its health goal of zero. Its highest single sample was 0.06 ppb. That is the only year on file.
What handles it
- NSF/ANSI 58 look for “Uranium”
Below EPA’s limits4
Total trihalomethanes (TTHM)
Forms or is added in treatment
7.7ppb
Highest yearly average, 2020 to 2026
2026, one sample: 2.0 ppb
Averaged by year, the highest was 7.7 ppb, in 2020, below EPA’s legal limit of 80 ppb. In 2026, the latest year on file, its one sample was 2.0 ppb. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 7.2 ppb, in 2019.
What handles it
- NSF/ANSI 53 look for “Trihalomethanes (TTHM) Reduction”
- NSF/ANSI 58 look for “Trihalomethanes (TTHM) Reduction”
Haloacetic acids (HAA5)
Forms or is added in treatment
2.9ppb
Highest yearly average, 2020 to 2026
2026, one sample: 1.0 ppb
Averaged by year, the highest was 2.9 ppb, in 2023, below EPA’s legal limit of 60 ppb. In 2026, the latest year on file, its one sample was 1.0 ppb. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 20.9 ppb, in 2015.
What handles it
No certification claim covers this compound yet.
Fluoride
Forms or is added in treatment
0.13ppm
Highest yearly average, 2020 to 2026
2026 average: 0.047 ppm
Averaged by year, the highest was 0.13 ppm, in 2023, below EPA’s legal limit of 4.0 ppm. Its highest single sample was 0.13 ppm. In 2026, the latest year on file, its two samples averaged 0.047 ppm. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 0.095 ppm, in 2017.
What handles it
- NSF/ANSI 58 look for “Fluoride Reduction”
- NSF/ANSI 53 look for “Fluoride”
Nitrate
Comes from the source
0.08ppm
Highest sample; found in 5 of 10
2025: not found
The highest sample, in 2022, was 0.08 ppm, below EPA’s legal limit of 10 ppm. In 2025, the latest year on file, it wasn’t found in any of its two samples. Earlier, from 2012 to 2019, EPA’s file shows a highest sample of 0.005 ppm, in 2018.
What handles it
- NSF/ANSI 58 look for “Nitrate/Nitrite Reduction”
- NSF/ANSI 53 look for “Nitrate/Nitrite (30 ppm challenge)”
3 compounds tested and not foundBelow the reporting level in every sample. Not found is not the same as zero.
- Arsenic
- Chromium (total)
- Lead
What handles it
A certification covers specific claims, not a whole standard. Look for these claims on the certifier’s listing, not the box. Wording varies a little: NSF writes “Lead Reduction,” WQA just “Lead.”
- NSF/ANSI 58
Claim: Uranium
For: Uranium
At the tap, or for the whole house?
These come with the water itself, so a whole-house system certified for the same claims treats every tap and shower. A filter at the tap treats drinking water for much less. How whole-house systems compare.
Filters with those claims on a certifier’s listing
None of the filters TapBuff has checked so far carry these claims. Search the certifier listings for the claim above.
Compare five-year costsHardness
Hard, typically 168 mg/L (9.8 grains per gallon), across 2 sampling points, 2017 to 2026.
Hardness is calcium and magnesium. EPA sets no limit for it: it shows up as scale on fixtures and in water heaters, and as soap that won’t lather. USGS calls water above 60 mg/L moderately hard, above 120 hard and above 180 very hard.
Violations since 2016
| Contaminant or rule | Type | Period | Measured | Status |
|---|---|---|---|---|
| Stage 1 Disinfectants and Disinfection Byproducts Rule | Treatment was not run by a certified operator as required.EPA: Treatment Technique No Certif. Operator | July 11, 2023 | — | Resolved |
| Stage 1 Disinfectants and Disinfection Byproducts Rule | Treatment was not run by a certified operator as required.EPA: Treatment Technique No Certif. Operator | Nov. 2, 2022 | — | Resolved |
| Health-based violations only. Resolved and archived mean the utility returned to compliance or the state closed the record. | ||||
What this report can’t tell you
Everything else. Total trihalomethanes (TTHM), haloacetic acids (HAA5), fluoride, nitrate, arsenic and chromium (total) results here are Wisconsin’s own from 2020 on, with EPA’s national file for 2012 to 2019. Uranium comes from EPA’s file alone, which ends in 2019. Wilton Waterworks’s own annual report, which it must send you every year, has newer results for those and the contaminants this page does not show.
Your own plumbing. Lead results are the 90th percentile across homes the utility samples. Your home’s service line, solder and fixtures decide yours. A certified lab test is the only way to know.
What it means for your health. This page reports what the records show and EPA’s limits and goals; it is not medical advice. If you are worried about a health effect, talk to a doctor or your local health department.
Anything after the latest data. SDWIS data is from 2026 Q3; UCMR 5 didn’t sample this utility; Wisconsin’s results run from April 14, 2020 to Sept. 15, 2026; EPA’s compliance samples are from March 16, 2017 to March 16, 2017.
Testing your own tap
The 3 labs Wisconsin certifies closest to the area Wilton Waterworks serves, in a straight line. Call first: certification is test by test, and not every lab takes samples from homeowners.
Monroe County Health Department
Sparta, WI · about 19 miles
Certified for bacteria
Leuther Laboratories LLC
Coon Valley, WI · about 27 miles
Certified for bacteria
A1 Advanced Pumping Service, Inc.
West Salem, WI · about 30 miles
Certified for bacteria, nitrate
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 WisconsinSources
- EPA UCMR 5 occurrence data, file of Oct. 15, 2026
- EPA SDWA bulk download (SDWIS federal data), 2026 Q3
- Wisconsin Department of Natural Resources, Drinking Water Program, results from Jan. 2, 2020 to Oct. 5, 2026, read Oct. 8, 2026
- EPA Six-Year Review 4 compliance monitoring data, 2012 to 2019, file of Feb. 5, 2024
- Certified labs: Wisconsin DNR and DATCP, certified and approved drinking water laboratories, read Oct. 10, 2026; distances from the Census 2020 ZIP code tabulation area gazetteer
- Hardness: Wisconsin Department of Natural Resources, Drinking Water Program, results from March 16, 2017 to July 16, 2026, read Oct. 10, 2026
- Limits and goals: each contaminant’s page, with its EPA source.
- How this page is built: methodology.
PWSID WI6420306. Rebuilt from EPA data on Oct. 18, 2026.
What to do next
- Read up on UraniumWhat each one does to health, where it comes from, and the certification claim that addresses it.About Uranium
- Get the utility’s own reportWilton Waterworks must send you a water quality report every year. It covers contaminants this page does not show, and has newer results than EPA’s national file for the ones here that come from it.How to read it
- Test your own tap for leadYour service line, solder and fixtures decide the lead at your faucet, not the utility’s average.Lead in your water: what to do
- Compare certified filtersWhat the filters certified for these results cost over five years, cartridges included.Compare five-year costs