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Knolls Water Cooperative

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
400 people
Connections
293
Water source
Groundwater
Based in
Powers Lake, WI
County
Kenosha
Owner
Private
Hardness
Very hard
The ZIP code it serves

53128

The short answer

2 results are above the health goal. The worst: Lead, above the health goal. No health-based violations on file since 2016.

What handles it

What was found

Lead and copper: EPA SDWIS monitoring periods ending 2008 to 2021.

Nitrate, total trihalomethanes (TTHM) and haloacetic acids (HAA5): Wisconsin’s own results, samples taken from March 20, 2020 to Sept. 25, 2026, with EPA’s 2012 to 2019 file for earlier years.

Uranium, arsenic, chromium (total) and fluoride: EPA’s compliance monitoring file, samples taken from April 6, 2015 to July 30, 2018. Newer results are in the utility’s annual water quality report.

Above the health goal2

Lead

Comes from pipes, often your own

Above the health goal

1.4ppb

90th percentile, 2021

In the latest period, 9 in 10 homes sampled were at or below 1.4 ppb, below EPA’s action level of 15 ppb. The action level drops to 10 ppb on Nov. 1, 2027. EPA’s health goal for lead is zero.

What handles it

Uranium

Comes from the source

Above the health goal

0.83ppb

Highest yearly average, 2015

Averaged by year, the highest was 0.83 ppb, in 2015: below EPA’s legal limit of 30 ppb, but above its health goal of zero. That is the only year on file.

What handles it

Below EPA’s limits3

Nitrate

Comes from the source

Below EPA’s limits

7.5ppm

Highest sample; found in 27 of 27

2026 average: 6.0 ppm

The highest sample, in 2025, was 7.5 ppm, below EPA’s legal limit of 10 ppm. In 2026, the latest year on file, its three samples averaged 6.0 ppm. Earlier, from 2012 to 2019, EPA’s file shows a highest sample of 7.5 ppm, in 2016.

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

6.9ppb

Highest yearly average, 2022 to 2025

Averaged by year, the highest was 6.9 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 6.4 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

0.86ppb

Highest yearly average, 2022 to 2025

2025: not found

Averaged by year, the highest was 0.86 ppb, in 2022, below EPA’s legal limit of 60 ppb. In 2025, the latest year on file, it wasn’t found in its one sample. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 2.4 ppb, in 2016.

What handles it

No certification claim covers this compound yet.

3 compounds tested and not foundBelow the reporting level in every sample. Not found is not the same as zero.
  • Arsenic
  • Chromium (total)
  • Fluoride

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.”

At the tap, or for the whole house?

Lead and copper usually come from pipes and fixtures inside or near your home. A whole-house system sits where water enters, so it cannot catch what your own plumbing adds after it. For those, the filter that counts is the one at the tap. How whole-house systems compare.

Filters with those claims on a certifier’s listing

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

Compare five-year costs

The best water filters for lead, ranked

Hardness

Very hard, 470 mg/L (27.5 grains per gallon), at its one sampling point, in 2018.

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 27.5 grains per gallon, salt includedSoftener 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) and haloacetic acids (HAA5) results here are Wisconsin’s own from 2020 on, with EPA’s national file for 2012 to 2019. Uranium, arsenic, chromium (total) and fluoride come from EPA’s file alone, which ends in 2019. Knolls Water Cooperative’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 March 20, 2020 to Sept. 25, 2026; EPA’s compliance samples are from April 6, 2015 to July 30, 2018.

Testing your own tap

Knolls Water Cooperative’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 Knolls Water Cooperative serves, in a straight line. Call first: certification is test by test, and not every lab takes samples from homeowners.

  • Lake Geneva Utility Commission

    Lake Geneva, WI · about 6 miles

    Certified for bacteria

    (262) 248-2311 ext. 406

  • Walworth Co. Health & Human Services

    Elkhorn, WI · about 17 miles

    Certified for bacteria, nitrate

    (262) 741-3200

  • S & R Krizan Pump Service Incorporated

    Wind Lake, WI · about 20 miles

    Certified for bacteria

    (262) 895-6454

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

Sources

PWSID WI2300145. Rebuilt from EPA data on Oct. 18, 2026.

Towns it serves

Also in Kenosha County

All Wisconsin utilities

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