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Green Valley MWC

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
2,993 people
Connections
1,070
Water source
Surface water bought from another system
Based in
Green Valley Lake, CA
County
San Bernardino
Owner
Private
Hardness
Varies by source
The ZIP code it serves

92341

The short answer

2 results are above EPA’s legal limit, and 1 more is above the health goal. The worst: Lead, above the action level. 1 health-based violation since 2016.

What handles it

What was found

Lead and copper: EPA SDWIS monitoring periods ending 2011 to 2020.

Copper: EPA’s file records a utility’s copper only when it exceeds the action level. The last here was 1.7 ppm, for the period ending June 30, 2019. None since is on file, so it is not counted as a current finding.

Uranium, arsenic, nitrate, total trihalomethanes (TTHM), haloacetic acids (HAA5), fluoride and chromium (total): California’s own results, samples taken from April 20, 2020 to May 20, 2026.

Above the legal limit2

Lead

Comes from pipes, often your own

Above the action level

24.9ppb

90th percentile, 2018 to 2020

In the latest period, 9 in 10 homes sampled were at or below 24.9 ppb, above EPA’s action level of 15 ppb. The action level drops to 10 ppb on Nov. 1, 2027, and this result is at or above that. EPA’s health goal for lead is zero.

What handles it

Uranium

Comes from the source

Above the legal limit

27.6ppb

Highest yearly average, 2020 to 2026

2026 average: 5.2 ppb

Averaged by year, the highest was 27.6 ppb, in 2024: below EPA’s legal limit of 30 ppb, but above its health goal of zero. Its highest single sample was 74.5 ppb. In 2026, the latest year on file, its two samples averaged 5.2 ppb. EPA judges this limit at each sampling point, and recorded a violation for uranium at this utility in 2024.

What handles it

Above the health goal1

Arsenic

Comes from the source

Above the health goal

2.5ppb

Highest yearly average, 2020 to 2025

2025: not found

Averaged by year, the highest was 2.5 ppb, in 2023: below EPA’s legal limit of 10 ppb, but above its health goal of zero. Its highest single sample was 6.2 ppb. In 2025, the latest year on file, it wasn’t found in any of its four samples.

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 limits4

Nitrate

Comes from the source

Below EPA’s limits

1.2ppm

Highest sample; found in 17 of 55

2026 average: 0.11 ppm

The highest sample, in 2022, was 1.2 ppm, below EPA’s legal limit of 10 ppm. In 2026, the latest year on file, its seven samples averaged 0.11 ppm.

What handles it

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

Total trihalomethanes (TTHM)

Forms or is added in treatment

Below EPA’s limits

7.5ppb

Highest yearly average, 2020 to 2026

2026, one sample: 6.7 ppb

Averaged by year, the highest was 7.5 ppb, in 2022, below EPA’s legal limit of 80 ppb. Its highest single sample was 8.6 ppb. In 2026, the latest year on file, its one sample was 6.7 ppb.

What handles it

  • NSF/ANSI 53 look for “Trihalomethanes (TTHM) Reduction”
  • NSF/ANSI 58 look for “Trihalomethanes (TTHM) Reduction”

Haloacetic acids (HAA5)

Forms or is added in treatment

Below EPA’s limits

4.5ppb

Highest yearly average, 2020 to 2026

2026, one sample: 3.9 ppb

Averaged by year, the highest was 4.5 ppb, in 2024, below EPA’s legal limit of 60 ppb. In 2026, the latest year on file, its one sample was 3.9 ppb.

What handles it

No certification claim covers this compound yet.

Fluoride

Forms or is added in treatment

Below EPA’s limits

0.11ppm

Highest yearly average, 2020 to 2025

2025: not found

Averaged by year, the highest was 0.11 ppm, in 2024, below EPA’s legal limit of 4.0 ppm. Its highest single sample was 0.13 ppm. In 2025, the latest year on file, it wasn’t found in any of its four samples.

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

    For: Lead, Arsenic

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

  • NSF/ANSI 58

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

    For: Lead, Uranium, Arsenic

    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 water filters for lead, ranked

The best reverse osmosis systems, ranked

Hardness

Soft to hard depending on the source, 21 to 170 mg/L (1.2 to 9.9 grains per gallon), across 9 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

Contaminant or ruleTypePeriodMeasuredStatus
Combined UraniumThe running average was above the legal limit.EPA: Maximum Contaminant Level Violation, AverageOct. 1, 2024 to Dec. 31, 202423.3 PCI/LArchived
Health-based violations only. Resolved and archived mean the utility returned to compliance or the state closed the record. 2 monitoring or reporting violations not shown.

What this report can’t tell you

  • Everything else. Uranium, arsenic, nitrate, total trihalomethanes (TTHM), haloacetic acids (HAA5), fluoride and chromium (total) results here are California’s own from 2020 on, with EPA’s national file for 2012 to 2019. Green Valley MWC’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 April 20, 2020 to May 20, 2026.

Testing your own tap

Green Valley MWC’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 Green Valley MWC serves, in a straight line. Call first: certification is test by test, and not every lab takes samples from homeowners.

  • BSK Associates - San Bernardino Analytical Laboratory

    San Bernardino, CA · about 17 miles

    Certified for bacteria

    (559) 497-2888

  • Geo-Monitor, Inc

    Hesperia, CA · about 20 miles

    Certified for bacteria

    (760) 244-3481

  • Clinical Laboratory of San Bernardino, Inc.

    Grand Terrace, CA · about 21 miles

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

    (909) 825-7693

All 145 certified labs for California

Sources

PWSID CA3610023. Rebuilt from EPA data on Oct. 18, 2026.

Also in San Bernardino County

All California utilities

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