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Park Heights 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
250 people
Connections
95
Water source
Groundwater
Based in
Modesto, CA
County
Stanislaus
Owner
Private
Hardness
Varies by source
The ZIP code it serves

95367

The short answer

2 results are 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

Arsenic, nitrate, chromium (total) and fluoride: California’s own results, samples taken from Aug. 4, 2020 to Dec. 18, 2025, with EPA’s 2012 to 2019 file for earlier years.

Uranium: EPA’s compliance monitoring file, samples taken from Dec. 28, 2012 to Dec. 28, 2012. Newer results are in the utility’s annual water quality report.

Above the health goal2

Uranium

Comes from the source

Above the health goal

12.4ppb

Highest yearly average, 2012

Averaged by year, the highest was 12.4 ppb, in 2012: 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

Arsenic

Comes from the source

Above the health goal

3.6ppb

Highest yearly average, 2020 to 2025

2025: not found

Averaged by year, the highest was 3.6 ppb, in 2022: below EPA’s legal limit of 10 ppb, but above its health goal of zero. Its highest single sample was 4.4 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 2.0 ppb, in 2013.

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 limits1

Nitrate

Comes from the source

Below EPA’s limits

3.0ppm

Highest sample; found in 5 of 13

2025 average: 1.4 ppm

The highest sample, in 2020, was 3.0 ppm, below EPA’s legal limit of 10 ppm. In 2025, the latest year on file, its two samples averaged 1.4 ppm. Earlier, from 2012 to 2019, EPA’s file shows a highest sample of 5.0 ppm, in 2013.

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.
  • Chromium (total)
  • Fluoride
  • 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 53

    Claim: Arsenic (Pentavalent)<=50 ppb Reduction

    For: Arsenic

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

  • NSF/ANSI 58

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

    For: Uranium, 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 to very hard depending on the source, 148 to 199 mg/L (8.7 to 11.6 grains per gallon), across 2 sampling points, 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, 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. Arsenic, nitrate, chromium (total) and fluoride results here are California’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. Park Heights Mutual Water Co’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; California’s results run from Aug. 4, 2020 to Dec. 18, 2025; EPA’s compliance samples are from Dec. 28, 2012 to Dec. 28, 2012.

Testing your own tap

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

  • Aemtek, Inc.

    Modesto, CA · about 4 miles

    Certified for bacteria

    (510) 979-1979

  • Institute of Environmental Health, Inc. dba IEH-JL Analytical

    Modesto, CA · about 7 miles

    Certified for bacteria, nitrate, minerals and other inorganics

    (209) 538-8111

  • Microbac Laboratories, Inc. - Turlock

    Turlock, CA · about 17 miles

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

    (707) 822-4649

All 145 certified labs for California

Sources

PWSID CA5000017. Rebuilt from EPA data on Oct. 18, 2026.

Towns it serves

Also in Stanislaus County

All California utilities

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