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Sonoma County CSA 41 - Freestone

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
90 people
Connections
26
Water source
Surface water
Based in
Santa Rosa, CA
County
Sonoma
Owner
Local government
Hardness
Varies by source
The ZIP code it serves

95472

The short answer

2 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 2010 to 2025.

Arsenic, total trihalomethanes (TTHM), haloacetic acids (HAA5), chromium (total), nitrate and fluoride: California’s own results, samples taken from Jan. 23, 2020 to April 21, 2026, with EPA’s 2012 to 2019 file for earlier years.

Above the health goal2

Lead

Comes from pipes, often your own

Above the health goal

6.0ppb

90th percentile, 2023 to 2025

In the latest period, 9 in 10 homes sampled were at or below 6.0 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

2.0ppb

Highest yearly average, 2020 to 2026

2026: not found

Averaged by year, the highest was 2.0 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, it wasn’t found in its one sample. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 4.5 ppb, in 2015.

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 limits5

Total trihalomethanes (TTHM)

Forms or is added in treatment

Below EPA’s limits

35ppb

Highest yearly average, 2020 to 2025

2025, one sample: 27 ppb

Averaged by year, the highest was 35 ppb, in 2020, below EPA’s legal limit of 80 ppb. In 2025, the latest year on file, its one sample was 27 ppb. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 89.3 ppb, in 2012, and EPA recorded violations in 2013 and 2014.

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

26ppb

Highest yearly average, 2020 to 2025

2025, one sample: 19 ppb

Averaged by year, the highest was 26 ppb, in 2020, below EPA’s legal limit of 60 ppb. In 2025, the latest year on file, its one sample was 19 ppb. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 86.6 ppb, in 2015, and EPA recorded violations in 2013 and 2015.

What handles it

No certification claim covers this compound yet.

Chromium (total)

Comes from the source

Below EPA’s limits

11ppb

Highest yearly average, 2020 to 2026

Averaged by year, the highest was 11 ppb, in 2026, below EPA’s legal limit of 100 ppb. That was also the latest year on file. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 9.3 ppb, in 2017.

What handles it

Nitrate

Comes from the source

Below EPA’s limits

0.67ppm

Highest sample; found in 5 of 20

2026: not found

The highest sample, in 2021, was 0.67 ppm, below EPA’s legal limit of 10 ppm. In 2026, the latest year on file, it wasn’t found in any of its three samples. Earlier, from 2012 to 2019, EPA’s file shows a highest sample of 1.4 ppm, in 2015.

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, 2020 to 2026

2026: not found

Averaged by year, the highest was 0.21 ppm, in 2020, below EPA’s legal limit of 4.0 ppm. In 2026, 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 0.26 ppm, in 2015.

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

    For: Lead, 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, 60 to 160 mg/L (3.5 to 9.4 grains per gallon), across 3 sampling points, 2019 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, 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. Arsenic, total trihalomethanes (TTHM), haloacetic acids (HAA5), chromium (total), nitrate and fluoride results here are California’s own from 2020 on, with EPA’s national file for 2012 to 2019. Sonoma County CSA 41 - Freestone’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. 23, 2020 to April 21, 2026.

Testing your own tap

Sonoma County CSA 41 - Freestone’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 Sonoma County CSA 41 - Freestone serves, in a straight line. Call first: certification is test by test, and not every lab takes samples from homeowners.

  • K Prime, LLC.

    Santa Rosa, CA · about 8 miles

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

    (707) 527-7574

  • Brelje and Race Laboratories, Inc.

    Santa Rosa, CA · about 9 miles

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

    (707) 544-8807

  • Sonoma County Public Health Laboratory

    Santa Rosa, CA · about 10 miles

    Certified for bacteria

    (707) 565-4711

All 145 certified labs for California

Sources

PWSID CA4900549. Rebuilt from EPA data on Oct. 18, 2026.

Also in Sonoma County

All California utilities

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