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Quiet Oaks Mobile Home Park

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
120 people
Connections
45
Water source
Groundwater
Based in
Stockton, CA
County
San Diego
Owner
Private
Hardness
Very hard
The ZIP code it serves

92086

The short answer

1 result is above EPA’s legal limit, and 1 more is above the health goal. The worst: Nitrate, above the legal limit. 40 health-based violations since 2016.

What handles it

What was found

Nitrate, uranium, fluoride, chromium (total), arsenic, haloacetic acids (HAA5) and total trihalomethanes (TTHM): California’s own results, samples taken from Jan. 22, 2020 to June 16, 2026, with EPA’s 2012 to 2019 file for earlier years.

Above the legal limit1

Nitrate

Comes from the source

Above the legal limit

18ppm

Highest sample; found in 64 of 65

2026 average: 3.2 ppm

From 2020 to 2025, at least 25 samples were above EPA’s legal limit of 10 ppm, the highest 18 ppm in 2022. The next sample at the same point, within 30 days, kept the average above the limit for 13; 12 have no follow-up sample on file within 30 days. In 2026, the latest year on file, its five samples averaged 3.2 ppm. EPA recorded violations for nitrate at this utility in 2020, 2021, 2022, 2023, 2024 and 2025. Earlier, from 2012 to 2019, EPA’s file shows a highest sample of 21 ppm, in 2012, and EPA recorded violations in 2013, 2014, 2015, 2016, 2017, 2018 and 2019.

What handles it

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

Above the health goal1

Uranium

Comes from the source

Above the health goal

11.3ppb

Highest yearly average, 2022

Averaged by year, the highest was 11.3 ppb, in 2022: below EPA’s legal limit of 30 ppb, but above its health goal of zero. That is the only year on file. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 44.4 ppb, in 2016.

What handles it

Below EPA’s limits2

Fluoride

Forms or is added in treatment

Below EPA’s limits

0.18ppm

Highest yearly average, 2021 to 2024

2024, one sample: 0.16 ppm

Averaged by year, the highest was 0.18 ppm, in 2021, below EPA’s legal limit of 4.0 ppm. In 2024, the latest year on file, its one sample was 0.16 ppm. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 0.3 ppm, in 2013.

What handles it

Chromium (total)

Comes from the source

Below EPA’s limits

2.0ppb

Highest yearly average, 2021 to 2024

2024: not found

Averaged by year, the highest was 2.0 ppb, in 2021, below EPA’s legal limit of 100 ppb. In 2024, 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 4.0 ppb, in 2013.

What handles it

4 compounds tested and not foundBelow the reporting level in every sample. Not found is not the same as zero.
  • Arsenic
  • Haloacetic acids (HAA5)
  • Lead
  • Total trihalomethanes (TTHM)

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: Nitrate/Nitrite (30 ppm challenge)

    For: Nitrate

  • NSF/ANSI 58

    Claims: Nitrate/Nitrite Reduction, Uranium

    For: Nitrate, Uranium

    Other certifiers’ wording: Nitrate

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

Very hard, 251 mg/L (14.7 grains per gallon), at its one sampling point, 2021 to 2024.

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 14.7 grains per gallon, salt includedSoftener or salt-free conditioner?California water hardness, utility by utility

Violations since 2016

Contaminant or ruleTypePeriodMeasuredStatus
NitrateA sample was above the legal limit, for a contaminant judged one sample at a time.EPA: Maximum Contaminant Level Violation, Single SampleJan. 1, 2025 to March 31, 202512 MG/LResolved
NitrateA sample was above the legal limit, for a contaminant judged one sample at a time.EPA: Maximum Contaminant Level Violation, Single SampleOct. 1, 2024 to Dec. 31, 202416 MG/LResolved
NitrateA sample was above the legal limit, for a contaminant judged one sample at a time.EPA: Maximum Contaminant Level Violation, Single SampleJuly 1, 2024 to Sept. 30, 202414 MG/LResolved
NitrateA sample was above the legal limit, for a contaminant judged one sample at a time.EPA: Maximum Contaminant Level Violation, Single SampleApril 1, 2024 to June 30, 202411 MG/LResolved
NitrateA sample was above the legal limit, for a contaminant judged one sample at a time.EPA: Maximum Contaminant Level Violation, Single SampleJan. 1, 2024 to March 31, 202411 MG/LResolved
NitrateA sample was above the legal limit, for a contaminant judged one sample at a time.EPA: Maximum Contaminant Level Violation, Single SampleOct. 1, 2023 to Dec. 31, 202311 MG/LResolved
NitrateA sample was above the legal limit, for a contaminant judged one sample at a time.EPA: Maximum Contaminant Level Violation, Single SampleJuly 1, 2023 to Sept. 30, 202312 MG/LResolved
NitrateA sample was above the legal limit, for a contaminant judged one sample at a time.EPA: Maximum Contaminant Level Violation, Single SampleApril 1, 2023 to June 30, 202312 MG/LResolved
NitrateA sample was above the legal limit, for a contaminant judged one sample at a time.EPA: Maximum Contaminant Level Violation, Single SampleJan. 1, 2023 to March 31, 202311 MG/LResolved
NitrateA sample was above the legal limit, for a contaminant judged one sample at a time.EPA: Maximum Contaminant Level Violation, Single SampleJuly 1, 2022 to Sept. 30, 202218 MG/LResolved
NitrateA sample was above the legal limit, for a contaminant judged one sample at a time.EPA: Maximum Contaminant Level Violation, Single SampleApril 1, 2022 to June 30, 202211 MG/LResolved
NitrateA sample was above the legal limit, for a contaminant judged one sample at a time.EPA: Maximum Contaminant Level Violation, Single SampleJan. 1, 2022 to March 31, 202212 MG/LResolved
NitrateA sample was above the legal limit, for a contaminant judged one sample at a time.EPA: Maximum Contaminant Level Violation, Single SampleOct. 1, 2021 to Dec. 31, 202111 MG/LResolved
NitrateA sample was above the legal limit, for a contaminant judged one sample at a time.EPA: Maximum Contaminant Level Violation, Single SampleJuly 1, 2021 to Sept. 30, 202114 MG/LResolved
NitrateA sample was above the legal limit, for a contaminant judged one sample at a time.EPA: Maximum Contaminant Level Violation, Single SampleApril 1, 2021 to June 30, 202111 MG/LResolved
NitrateA sample was above the legal limit, for a contaminant judged one sample at a time.EPA: Maximum Contaminant Level Violation, Single SampleJan. 1, 2021 to March 31, 202114 MG/LResolved
NitrateA sample was above the legal limit, for a contaminant judged one sample at a time.EPA: Maximum Contaminant Level Violation, Single SampleOct. 1, 2020 to Dec. 31, 202014 MG/LResolved
NitrateA sample was above the legal limit, for a contaminant judged one sample at a time.EPA: Maximum Contaminant Level Violation, Single SampleJuly 1, 2020 to Sept. 30, 202011 MG/LResolved
NitrateA sample was above the legal limit, for a contaminant judged one sample at a time.EPA: Maximum Contaminant Level Violation, Single SampleApril 1, 2020 to June 30, 202011 MG/LResolved
NitrateA sample was above the legal limit, for a contaminant judged one sample at a time.EPA: Maximum Contaminant Level Violation, Single SampleJan. 1, 2020 to March 31, 202011 MG/LResolved
NitrateA sample was above the legal limit, for a contaminant judged one sample at a time.EPA: Maximum Contaminant Level Violation, Single SampleOct. 1, 2019 to Dec. 31, 201911 MG/LResolved
NitrateA sample was above the legal limit, for a contaminant judged one sample at a time.EPA: Maximum Contaminant Level Violation, Single SampleJuly 1, 2019 to Sept. 30, 201911 MG/LResolved
NitrateA sample was above the legal limit, for a contaminant judged one sample at a time.EPA: Maximum Contaminant Level Violation, Single SampleMay 1, 2019 to May 31, 201912 MG/LResolved
NitrateA sample was above the legal limit, for a contaminant judged one sample at a time.EPA: Maximum Contaminant Level Violation, Single SampleApril 1, 2019 to April 30, 201912 MG/LResolved
NitrateA sample was above the legal limit, for a contaminant judged one sample at a time.EPA: Maximum Contaminant Level Violation, Single SampleMarch 1, 2019 to March 31, 201912 MG/LResolved
NitrateA sample was above the legal limit, for a contaminant judged one sample at a time.EPA: Maximum Contaminant Level Violation, Single SampleFeb. 1, 2019 to Feb. 28, 201915 MG/LResolved
NitrateA sample was above the legal limit, for a contaminant judged one sample at a time.EPA: Maximum Contaminant Level Violation, Single SampleJan. 1, 2019 to Jan. 31, 201912 MG/LResolved
NitrateA sample was above the legal limit, for a contaminant judged one sample at a time.EPA: Maximum Contaminant Level Violation, Single SampleSept. 1, 2018 to Sept. 30, 201810 MG/LResolved
NitrateA sample was above the legal limit, for a contaminant judged one sample at a time.EPA: Maximum Contaminant Level Violation, Single SampleAug. 1, 2018 to Aug. 31, 201810 MG/LResolved
NitrateA sample was above the legal limit, for a contaminant judged one sample at a time.EPA: Maximum Contaminant Level Violation, Single SampleJuly 1, 2018 to July 31, 201812 MG/LResolved
Nitrate-NitriteA sample was above the legal limit, for a contaminant judged one sample at a time.EPA: Maximum Contaminant Level Violation, Single SampleApril 1, 2018 to June 30, 201811 MG/LResolved
Nitrate-NitriteA sample was above the legal limit, for a contaminant judged one sample at a time.EPA: Maximum Contaminant Level Violation, Single SampleJan. 1, 2018 to March 31, 201810 MG/LResolved
Nitrate-NitriteA sample was above the legal limit, for a contaminant judged one sample at a time.EPA: Maximum Contaminant Level Violation, Single SampleOct. 1, 2017 to Dec. 31, 201710 MG/LResolved
NitrateA sample was above the legal limit, for a contaminant judged one sample at a time.EPA: Maximum Contaminant Level Violation, Single SampleJuly 1, 2017 to Sept. 30, 201710.1 MG/LResolved
NitrateA sample was above the legal limit, for a contaminant judged one sample at a time.EPA: Maximum Contaminant Level Violation, Single SampleApril 1, 2017 to June 30, 201711 MG/LResolved
NitrateA sample was above the legal limit, for a contaminant judged one sample at a time.EPA: Maximum Contaminant Level Violation, Single SampleJan. 1, 2017 to March 31, 201714 MG/LResolved
NitrateA sample was above the legal limit, for a contaminant judged one sample at a time.EPA: Maximum Contaminant Level Violation, Single SampleOct. 1, 2016 to Dec. 31, 201611 MG/LResolved
NitrateA sample was above the legal limit, for a contaminant judged one sample at a time.EPA: Maximum Contaminant Level Violation, Single SampleJuly 1, 2016 to Sept. 30, 201612 MG/LResolved
NitrateA sample was above the legal limit, for a contaminant judged one sample at a time.EPA: Maximum Contaminant Level Violation, Single SampleApril 1, 2016 to June 30, 201615 MG/LResolved
NitrateA sample was above the legal limit, for a contaminant judged one sample at a time.EPA: Maximum Contaminant Level Violation, Single SampleJan. 1, 2016 to March 31, 201614 MG/LResolved
Health-based violations only. Resolved and archived mean the utility returned to compliance or the state closed the record.

What this report can’t tell you

  • Everything else. Nitrate, uranium, fluoride, chromium (total), arsenic, haloacetic acids (HAA5) and total trihalomethanes (TTHM) results here are California’s own from 2020 on, with EPA’s national file for 2012 to 2019. Quiet Oaks Mobile Home Park’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 Jan. 22, 2020 to June 16, 2026.

Testing your own tap

Quiet Oaks Mobile Home Park’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 Quiet Oaks Mobile Home Park serves, in a straight line. Call first: certification is test by test, and not every lab takes samples from homeowners.

  • Applied Industrial Microbiology, Inc.

    Vista, CA · about 35 miles

    Certified for bacteria, nitrate

    (760) 295-0430

  • Alpha Analytical Laboratories, Inc. - San Diego

    Vista, CA · about 37 miles

    Certified for bacteria, nitrate, minerals and other inorganics

    (760) 536-3352

  • EMSL Analytical, Inc.

    San Diego, CA · about 44 miles

    Certified for bacteria

    (800) 220-3675

All 145 certified labs for California

Sources

PWSID CA3701341. Rebuilt from EPA data on Oct. 18, 2026.

Also in San Diego County

All California utilities

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