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Clear Water Mutual Water Company

What EPA’s and California’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
154 people
Connections
89
Water source
Surface water
Based in
Kelseyville, CA
County
Lake
Owner
Private
Hardness
Hard
The ZIP code it serves

95451

The short answer

1 result is above the limit’s level with no violation recorded, and 1 more is above the health goal. The worst: Total trihalomethanes (TTHM), above the limit’s level, no violation. No health-based violations on file since 2016.

What handles it

What was found

Total trihalomethanes (TTHM), arsenic, haloacetic acids (HAA5), fluoride, chromium (total) and nitrate: California’s own results, samples taken from July 21, 2020 to July 15, 2025, with EPA’s 2012 to 2019 file for earlier years.

Above the limit’s level, no violation recorded1

Total trihalomethanes (TTHM)

Forms or is added in treatment

Above the limit’s level, no violation

85ppb

Highest yearly average, 2020 to 2025

2025, one sample: 51 ppb

Averaged by year, the highest was 85 ppb, in 2023, above EPA’s legal limit of 80 ppb. In 2025, the latest year on file, its one sample was 51 ppb. EPA judges this limit on running averages at each sampling point, and recorded no violation for total trihalomethanes (TTHM) at this utility since 2020. Results like these with no violation often include water sampled before treatment or blending; the utility’s annual report says what reaches the tap. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 69 ppb, in 2014.

What handles it

  • NSF/ANSI 53 look for “Trihalomethanes (TTHM) Reduction”
  • NSF/ANSI 58 look for “Trihalomethanes (TTHM) Reduction”

Above the health goal1

Arsenic

Comes from the source

Above the health goal

5.4ppb

Highest yearly average, 2020 to 2025

Averaged by year, the highest was 5.4 ppb, in 2025: below EPA’s legal limit of 10 ppb, but above its health goal of zero. That was also the latest year on file. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 4.8 ppb, in 2015.

What handles it

  • NSF/ANSI 58 look for “Arsenic (Pentavalent)<=50 ppb Reduction”
  • NSF/ANSI 53 look for “Arsenic (Pentavalent)<=50 ppb Reduction”

Below EPA’s limits2

Haloacetic acids (HAA5)

Forms or is added in treatment

Below EPA’s limits

25.5ppb

Highest yearly average, 2020 to 2025

2025, one sample: 17 ppb

Averaged by year, the highest was 25.5 ppb, in 2024, below EPA’s legal limit of 60 ppb. Its highest single sample was 32 ppb. In 2025, the latest year on file, its one sample was 17 ppb. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 39.2 ppb, in 2013.

What handles it

No certification claim covers this compound yet.

Fluoride

Forms or is added in treatment

Below EPA’s limits

0.34ppm

Highest yearly average, 2020 to 2025

2025: not found

Averaged by year, the highest was 0.34 ppm, in 2020, below EPA’s legal limit of 4.0 ppm. 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 0.25 ppm, in 2015.

What handles it

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

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 53

    Claims: Trihalomethanes (TTHM) Reduction, Arsenic (Pentavalent)<=50 ppb Reduction

    For: Total trihalomethanes (TTHM), Arsenic

    Other certifiers’ wording: VOC Reduction; Arsenic (III) (50 ppb influent level)

  • NSF/ANSI 58

    Claims: Trihalomethanes (TTHM) Reduction, Arsenic (Pentavalent)<=50 ppb Reduction

    For: Total trihalomethanes (TTHM), Arsenic

    Other certifiers’ wording: Arsenic (Pentavalent)<=300 ppb Reduction; Arsenic (V) (300 ppb influent level)

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

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 reverse osmosis systems, ranked

Hardness

Hard, 140 mg/L (8.2 grains per gallon), at its one sampling point, 2019 to 2025.

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 8.2 grains per gallon, salt includedSoftener or salt-free conditioner?California 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. Total trihalomethanes (TTHM), arsenic, haloacetic acids (HAA5), fluoride, chromium (total) and nitrate results here are California’s own from 2020 on, with EPA’s national file for 2012 to 2019. Clear Water Mutual Water Company’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; California’s results run from July 21, 2020 to July 15, 2025.

Testing your own tap

Clear Water Mutual Water Company’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 California certifies.

The 3 labs California certifies closest to the area Clear Water Mutual Water Company serves, in a straight line. Call first: certification is test by test, and not every lab takes samples from homeowners.

  • Alpha Analytical Laboratories, Inc. - Ukiah

    Ukiah, CA · about 27 miles

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

    (707) 468-0401

  • K Prime, LLC.

    Santa Rosa, CA · about 29 miles

    Certified for bacteria, nitrate, lead and copper, metals, minerals and other inorganics, PFAS

    (707) 527-7574

  • Sonoma County Public Health Laboratory

    Santa Rosa, CA · about 32 miles

    Certified for bacteria

    (707) 565-4711

All 145 certified labs for California

Sources

PWSID CA1700546. Rebuilt from EPA data on Oct. 18, 2026.

Towns it serves

Also in Lake County

All California utilities

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