Skip to content
TapBuff
ZIP

Zone 7 Water Agency

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
40 people
Connections
12
Water source
Surface water
Based in
Livermore, CA
County
Alameda
Owner
Local government
The 8 ZIP codes it serves

94514, 94550, 94551, 94566, 94568, 94582, 94586, 94588

The short answer

3 results are above the health goal. The worst: Lead, above the health goal. No health-based violations on file since 2016.

What handles it

What was found

Lead and copper: EPA SDWIS monitoring periods ending 2008 to 2021.

Arsenic, uranium, nitrate, total trihalomethanes (TTHM), haloacetic acids (HAA5), chromium (total) and fluoride: California’s own results, samples taken from Jan. 6, 2020 to June 2, 2026, with EPA’s 2012 to 2019 file for earlier years.

Above the health goal3

Lead

Comes from pipes, often your own

Above the health goal

6.7ppb

90th percentile, 2019 to 2021

In the latest period, 9 in 10 homes sampled were at or below 6.7 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

Arsenic

Comes from the source

Above the health goal

1.8ppb

Highest yearly average, 2020 to 2026

2026 average: 0.4 ppb

Averaged by year, the highest was 1.8 ppb, in 2023: below EPA’s legal limit of 10 ppb, but above its health goal of zero. Its highest single sample was 7.8 ppb. In 2026, the latest year on file, its 40 samples averaged 0.4 ppb. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 1.2 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”

Uranium

Comes from the source

Above the health goal

1.2ppb

Highest yearly average, 2020 to 2026

2026 average: 0.65 ppb

Averaged by year, the highest was 1.2 ppb, in 2021: below EPA’s legal limit of 30 ppb, but above its health goal of zero. Its highest single sample was 6.6 ppb. In 2026, the latest year on file, its 40 samples averaged 0.65 ppb. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 1.3 ppb, in 2013.

What handles it

Below EPA’s limits5

Nitrate

Comes from the source

Below EPA’s limits

4.9ppm

Highest sample; found in 283 of 493

2026 average: 1.9 ppm

The highest sample, in 2025, was 4.9 ppm, below EPA’s legal limit of 10 ppm. In 2026, the latest year on file, its 40 samples averaged 1.9 ppm. Earlier, from 2012 to 2019, EPA’s file shows a highest sample of 11.5 ppm, in 2013.

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

34.1ppb

Highest yearly average, 2020 to 2026

2026 average: 25.5 ppb

Averaged by year, the highest was 34.1 ppb, in 2025, below EPA’s legal limit of 80 ppb. Its highest single sample was 55 ppb. In 2026, the latest year on file, its eight samples averaged 25.5 ppb. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 26.4 ppb, in 2015.

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

23.5ppb

Highest yearly average, 2022 to 2026

2026 average: 13.9 ppb

Averaged by year, the highest was 23.5 ppb, in 2023, below EPA’s legal limit of 60 ppb. Its highest single sample was 46 ppb. In 2026, the latest year on file, its eight samples averaged 13.9 ppb.

What handles it

No certification claim covers this compound yet.

Chromium (total)

Comes from the source

Below EPA’s limits

5.0ppb

Highest yearly average, 2020 to 2026

2026 average: 0.8 ppb

Averaged by year, the highest was 5.0 ppb, in 2024, below EPA’s legal limit of 100 ppb. Its highest single sample was 81 ppb. In 2026, the latest year on file, its 40 samples averaged 0.8 ppb. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 2.6 ppb, in 2019.

What handles it

Fluoride

Forms or is added in treatment

Below EPA’s limits

0.048ppm

Highest yearly average, 2020 to 2026

2026 average: 0.011 ppm

Averaged by year, the highest was 0.048 ppm, in 2021, below EPA’s legal limit of 4.0 ppm. Its highest single sample was 0.23 ppm. In 2026, the latest year on file, its 40 samples averaged 0.011 ppm. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 0.1 ppm, in 2014.

What handles it

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

    For: Lead, Arsenic, Uranium

    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

Violations since 2016

No health-based violations on file with EPA since 2016.

What this report can’t tell you

  • Everything else. Arsenic, uranium, nitrate, total trihalomethanes (TTHM), haloacetic acids (HAA5), chromium (total) and fluoride results here are California’s own from 2020 on, with EPA’s national file for 2012 to 2019. Zone 7 Water Agency’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. 6, 2020 to June 2, 2026.

Testing your own tap

Zone 7 Water Agency’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 Zone 7 Water Agency serves, in a straight line. Call first: certification is test by test, and not every lab takes samples from homeowners.

  • Alpha Analytical Laboratories, Inc.

    Livermore, CA · about 6 miles

    Certified for bacteria

    (707) 769-3128

  • AEMTEK, Inc

    Fremont, CA · about 16 miles

    Certified for bacteria, minerals and other inorganics

    (510) 979-1979

  • SGS North America

    Hayward, CA · about 19 miles

    Certified for bacteria

    (510) 266-8183

All 145 certified labs for California

Sources

PWSID CA0110010. Rebuilt from EPA data on Oct. 18, 2026.

Towns it serves

Also in Alameda County

All California utilities

What to do next