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Fourth Street 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
12 people
Connections
29
Water source
Groundwater
Based in
Lake Isabella, CA
County
Kern
Owner
Private
Hardness
Moderately hard
The ZIP code it serves

93285

The short answer

1 result is above the limit’s level with no violation recorded, and 2 more are above the health goal. The worst: Arsenic, above the limit’s level, no violation. 3 health-based violations since 2016.

What handles it

What was found

Lead and copper: EPA SDWIS monitoring periods ending 2008 to 2025.

Arsenic, uranium, nitrate, fluoride and chromium (total): California’s own results, samples taken from Jan. 21, 2020 to April 28, 2026, with EPA’s 2012 to 2019 file for earlier years.

Above the limit’s level, no violation recorded1

Arsenic

Comes from the source

Above the limit’s level, no violation

15ppb

Highest yearly average, 2022 to 2025

2025: not found

Averaged by year, the highest was 15 ppb, in 2023, above EPA’s legal limit of 10 ppb. In 2025, the latest year on file, it wasn’t found in its one sample. EPA judges this limit on running averages at each sampling point, and recorded no violation for arsenic 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 15.9 ppb, in 2015, and EPA recorded violations in 2012, 2013, 2014, 2015 and 2016.

What handles it

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

Above the health goal2

Uranium

Comes from the source

Above the health goal

5.8ppb

Highest yearly average, 2023

Averaged by year, the highest was 5.8 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. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 5.7 ppb, in 2017.

What handles it

Lead

Comes from pipes, often your own

Above the health goal

0.7ppb

90th percentile, 2023 to 2025

In the latest period, 9 in 10 homes sampled were at or below 0.7 ppb, below EPA’s action level of 15 ppb. The action level drops to 10 ppb on Nov. 1, 2027. EPA’s health goal for lead is zero.

What handles it

Below EPA’s limits2

Nitrate

Comes from the source

Below EPA’s limits

10ppm

Highest sample; found in 32 of 32

2026 average: 6.5 ppm

The highest sample, in 2022, was 10 ppm, below EPA’s legal limit of 10 ppm. In 2026, the latest year on file, its two samples averaged 6.5 ppm. Earlier, from 2012 to 2019, EPA’s file shows a highest sample of 13 ppm, in 2018.

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

0.21ppm

Highest yearly average, 2022 to 2025

2025, one sample: 0.2 ppm

Averaged by year, the highest was 0.21 ppm, in 2023, below EPA’s legal limit of 4.0 ppm. In 2025, the latest year on file, its one sample was 0.2 ppm. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 0.27 ppm, in 2014.

What handles it

One compound tested and not foundBelow the reporting level in every sample. Not found is not the same as zero.
  • Chromium (total)

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: Arsenic (Pentavalent)<=50 ppb Reduction, Lead Reduction

    For: Arsenic, Lead

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

  • NSF/ANSI 58

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

    For: Arsenic, Uranium, Lead

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

At the tap, or for the whole house?

Lead and copper usually come from pipes and fixtures inside or near your home. A whole-house system sits where water enters, so it cannot catch what your own plumbing adds after it. For those, the filter that counts is the one at the tap. 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

The best water filters for lead, ranked

Hardness

Moderately hard, 120 mg/L (7 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 7 grains per gallon, salt includedSoftener or salt-free conditioner?California water hardness, utility by utility

Violations since 2016

Contaminant or ruleTypePeriodMeasuredStatus
ArsenicThe running average was above the legal limit.EPA: Maximum Contaminant Level Violation, AverageJuly 1, 2016 to Sept. 30, 20160.017 MG/LResolved
ArsenicThe running average was above the legal limit.EPA: Maximum Contaminant Level Violation, AverageApril 1, 2016 to July 30, 20160.018 MG/LResolved
ArsenicThe running average was above the legal limit.EPA: Maximum Contaminant Level Violation, AverageJan. 1, 2016 to March 31, 20160.018 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. Arsenic, uranium, nitrate, fluoride and chromium (total) results here are California’s own from 2020 on, with EPA’s national file for 2012 to 2019. Fourth Street 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 Jan. 21, 2020 to April 28, 2026.

Testing your own tap

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

  • Pace Analytical Services, LLC dba BC Laboratories, Inc.

    Bakersfield, CA · about 37 miles

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

    (661) 327-4911

  • Zalco Laboratories, Inc.

    Bakersfield, CA · about 37 miles

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

    (661) 395-0539

  • BSK Associates - Bakersfield Analytical Laboratory

    Bakersfield, CA · about 42 miles

    Certified for bacteria

    (661) 327-0671

All 145 certified labs for California

Sources

PWSID CA1500449. Rebuilt from EPA data on Oct. 18, 2026.

Towns it serves

Also in Kern County

All California utilities

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