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Belleview Oaks Mutual Water Co

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
468 people
Connections
167
Water source
Groundwater
Based in
Sonora, CA
County
Tuolumne
Owner
Private
Hardness
Varies by source
The ZIP code it serves

95370

The short answer

1 result is above the health goal. The worst: Uranium, above the health goal. No health-based violations on file since 2016.

What handles it

What was found

Uranium, nitrate, fluoride, arsenic and chromium (total): California’s own results, samples taken from Dec. 3, 2020 to Feb. 3, 2025, with EPA’s 2012 to 2019 file for earlier years.

Above the health goal1

Uranium

Comes from the source

Above the health goal

6.9ppb

Highest yearly average, 2023

Averaged by year, the highest was 6.9 ppb, in 2023: 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 limits2

Nitrate

Comes from the source

Below EPA’s limits

2.2ppm

Highest sample; found in 19 of 24

2025 average: 1.2 ppm

The highest sample, in 2025, was 2.2 ppm, below EPA’s legal limit of 10 ppm. That was also the latest year on file, and its eight samples averaged 1.2 ppm. Earlier, from 2012 to 2019, EPA’s file shows a highest sample of 3.5 ppm, in 2019.

What handles it

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

Fluoride

Forms or is added in treatment

Below EPA’s limits

0.14ppm

Highest yearly average, 2021 to 2025

2025: not found

Averaged by year, the highest was 0.14 ppm, in 2021, below EPA’s legal limit of 4.0 ppm. Its highest single sample was 0.18 ppm. In 2025, the latest year on file, it wasn’t found in any of its four samples. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 0.068 ppm, in 2018.

What handles it

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.”

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 costs

Hardness

Soft to very hard depending on the source, 52 to 202 mg/L (3.1 to 11.8 grains per gallon), across 4 sampling points, 2021 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, 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. There is 1 monitoring or reporting violation: a sample missed, late or not reported.

What this report can’t tell you

  • Everything else. Uranium, nitrate, fluoride, arsenic and chromium (total) results here are California’s own from 2020 on, with EPA’s national file for 2012 to 2019. Belleview Oaks Mutual Water Co’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 Dec. 3, 2020 to Feb. 3, 2025.

Testing your own tap

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

  • Precision Enviro-Tech

    Twain Harte, CA · about 8 miles

    Certified for bacteria

    (209) 477-8105

  • 49er Water Laboratory

    Jackson, CA · about 34 miles

    Certified for bacteria, nitrate, minerals and other inorganics

    (530) 277-2770

  • Aemtek, Inc.

    Modesto, CA · about 41 miles

    Certified for bacteria

    (510) 979-1979

All 145 certified labs for California

Sources

PWSID CA5500042. Rebuilt from EPA data on Oct. 18, 2026.

Towns it serves

Also in Tuolumne County

All California utilities

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