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Elkhorn Estates Water System

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
234 people
Connections
71
Water source
Groundwater
Based in
Stockton, CA
County
San Joaquin
Owner
Local government
Hardness
Very hard
The ZIP code it serves

95209

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

Uranium, arsenic, nitrate, chromium (total), fluoride, haloacetic acids (HAA5) and total trihalomethanes (TTHM): California’s own results, samples taken from Feb. 20, 2020 to March 2, 2026, with EPA’s 2012 to 2019 file for earlier years.

Above the health goal2

Uranium

Comes from the source

Above the health goal

25.2ppb

Highest yearly average, 2020 to 2026

2026, one sample: 20.1 ppb

Averaged by year, the highest was 25.2 ppb, in 2021: below EPA’s legal limit of 30 ppb, but above its health goal of zero. Its highest single sample was 27 ppb. In 2026, the latest year on file, its one sample was 20.1 ppb. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 21.7 ppb, in 2019.

What handles it

Arsenic

Comes from the source

Above the health goal

4.0ppb

Highest yearly average, 2020 to 2026

2026, one sample: 3.0 ppb

Averaged by year, the highest was 4.0 ppb, in 2020: below EPA’s legal limit of 10 ppb, but above its health goal of zero. In 2026, the latest year on file, its one sample was 3.0 ppb. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 4.0 ppb, in 2014.

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

Nitrate

Comes from the source

Below EPA’s limits

7.0ppm

Highest sample; found in 15 of 15

2026 average: 6.9 ppm

The highest sample, in 2025, was 7.0 ppm, below EPA’s legal limit of 10 ppm. In 2026, the latest year on file, its two samples averaged 6.9 ppm. Earlier, from 2012 to 2019, EPA’s file shows a highest sample of 5.1 ppm, in 2018.

What handles it

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

Chromium (total)

Comes from the source

Below EPA’s limits

18ppb

Highest yearly average, 2020 to 2026

2026, one sample: 11 ppb

Averaged by year, the highest was 18 ppb, in 2023, below EPA’s legal limit of 100 ppb. In 2026, the latest year on file, its one sample was 11 ppb. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 7.0 ppb, in 2015.

What handles it

4 compounds tested and not foundBelow the reporting level in every sample. Not found is not the same as zero.
  • Fluoride
  • 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: 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

Very hard, typically 283 mg/L (16.6 grains per gallon), across 2 sampling points, 2020 to 2026.

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 16.6 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. Uranium, arsenic, nitrate, chromium (total), fluoride, 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. Elkhorn Estates Water System’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 Feb. 20, 2020 to March 2, 2026.

Testing your own tap

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

  • Precision Enviro-Tech

    Stockton, CA · about 5 miles

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

    (209) 405-0601

  • Lodi Wine Laboratories

    Lodi, CA · about 8 miles

    Certified for nitrate, minerals and other inorganics

    (209) 339-1990

  • San Joaquin County Public Health Laboratory

    Stockton, CA · about 8 miles

    Certified for bacteria

    (209) 468-3460

All 145 certified labs for California

Sources

PWSID CA3900724. Rebuilt from EPA data on Oct. 18, 2026.

Towns it serves

Also in San Joaquin County

All California utilities

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