Rocky Knoll Health Care Fac

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: 564 people
Connections: 208
Water source: Groundwater
Based in: Plymouth, WI
County: Sheboygan
Owner: Local government
Hardness: Very hard

The ZIP code it serves

53083

The short answer

Nothing in EPA’s and Wisconsin’s records for this utility is above a health goal. That covers nitrate, arsenic and other regulated chemicals, plus lead and copper, not everything. No health-based violations on file since 2016.

What was found

Copper: EPA’s file records a utility’s copper only when it exceeds the action level. The last here was 2.0 ppm, for the period ending Dec. 31, 1999. None since is on file, so it is not counted as a current finding.

Nitrate, total trihalomethanes (TTHM), haloacetic acids (HAA5), fluoride, arsenic and chromium (total): Wisconsin’s own results, samples taken from Aug. 11, 2020 to Aug. 18, 2026, with EPA’s 2012 to 2019 file for earlier years.

Below EPA’s limits4

Nitrate

Comes from the source

Below EPA’s limits

1.1ppm

Highest sample; found in 7 of 10

2025: not found

The highest sample, in 2022, was 1.1 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 1.3 ppm, in 2012.

What handles it

NSF/ANSI 58 look for “Nitrate/Nitrite Reduction”
NSF/ANSI 53 look for “Nitrate/Nitrite (30 ppm challenge)”

Total trihalomethanes (TTHM)

Forms or is added in treatment

Below EPA’s limits

5.4ppb

Highest yearly average, 2022 to 2025

Averaged by year, the highest was 5.4 ppb, in 2025, below EPA’s legal limit of 80 ppb. That was also the latest year on file. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 6.6 ppb, in 2016.

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

Below EPA’s limits

2.3ppb

Highest yearly average, 2022 to 2025

Averaged by year, the highest was 2.3 ppb, in 2025, below EPA’s legal limit of 60 ppb. That was also the latest year on file. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 8.1 ppb, in 2019.

What handles it

No certification claim covers this compound yet.

Fluoride

Forms or is added in treatment

Below EPA’s limits

0.12ppm

Highest yearly average, 2020 to 2026

2026: not found

Averaged by year, the highest was 0.12 ppm, in 2020, below EPA’s legal limit of 4.0 ppm. Its highest single sample was 0.14 ppm. In 2026, 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 yearly average of 0.14 ppm, in 2017.

What handles it

NSF/ANSI 58 look for “Fluoride Reduction”
NSF/ANSI 53 look for “Fluoride”

3 compounds tested and not foundBelow the reporting level in every sample. Not found is not the same as zero.

Arsenic
Chromium (total)
Lead

Hardness

Very hard, typically 313 mg/L (18.3 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.

Softeners compared at 18.3 grains per gallon, salt included Softener or salt-free conditioner?Wisconsin water hardness, utility by utility

Violations since 2016

No health-based violations on file with EPA since 2016.

What this report can’t tell you

Everything else. Nitrate, total trihalomethanes (TTHM), haloacetic acids (HAA5), fluoride, arsenic and chromium (total) results here are Wisconsin’s own from 2020 on, with EPA’s national file for 2012 to 2019. Rocky Knoll Health Care Fac’s own annual report, which it must send you every year, has 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 Aug. 11, 2020 to Aug. 18, 2026.

Testing your own tap

Rocky Knoll Health Care Fac’s results are for the water it sends out. What your own service line, solder and fixtures add shows up only in a test of your tap, by a lab Wisconsin certifies.

The 3 labs Wisconsin certifies closest to the area Rocky Knoll Health Care Fac serves, in a straight line. Call first: certification is test by test, and not every lab takes samples from homeowners.

Kohler Co., CHEM Lab
Kohler, WI · about 5 miles
Certified for bacteria, nitrate, lead and copper, metals, minerals and other inorganics
(920) 457-4441
Washington Ozaukee Public Health Department
Port Washington, WI · about 28 miles
Certified for bacteria
(262) 284-8170
Washington Ozaukee Public Health Department
West Bend, WI · about 28 miles
Certified for bacteria
(262) 284-8170

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