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Rolling Oaks Road Association

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
25 people
Connections
16
Water source
Groundwater
Based in
Rohnert Park, CA
County
Sonoma
Owner
Private
Hardness
Varies by source
The ZIP code it serves

95404

The short answer

1 result is above the limit’s level with no violation recorded. The worst: Arsenic, above the limit’s level, no violation. No health-based violations on file since 2016.

What handles it

What was found

Arsenic, haloacetic acids (HAA5), chromium (total), total trihalomethanes (TTHM), fluoride, nitrate and uranium: California’s own results, samples taken from Sept. 24, 2020 to Dec. 2, 2025, 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

44ppb

Highest yearly average, 2020 to 2025

2025, one sample: 6.3 ppb

Averaged by year, the highest was 44 ppb, in 2020, about 4.4 times EPA’s legal limit of 10 ppb. In 2025, the latest year on file, its one sample was 6.3 ppb. 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 4.7 ppb, in 2018.

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 limits3

Haloacetic acids (HAA5)

Forms or is added in treatment

Below EPA’s limits

24.7ppb

Highest yearly average, 2021 to 2024

2024: not found

Averaged by year, the highest was 24.7 ppb, in 2021, below EPA’s legal limit of 60 ppb. In 2024, 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 2.2 ppb, in 2018.

What handles it

No certification claim covers this compound yet.

Chromium (total)

Comes from the source

Below EPA’s limits

20ppb

Highest yearly average, 2020 to 2024

2024, one sample: 1.3 ppb

Averaged by year, the highest was 20 ppb, in 2020, below EPA’s legal limit of 100 ppb. In 2024, the latest year on file, its one sample was 1.3 ppb.

What handles it

Total trihalomethanes (TTHM)

Forms or is added in treatment

Below EPA’s limits

7.5ppb

Highest yearly average, 2021 to 2024

Averaged by year, the highest was 7.5 ppb, in 2024, below EPA’s legal limit of 80 ppb. That was also the latest year on file. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 3.5 ppb, in 2012.

What handles it

  • NSF/ANSI 53 look for “Trihalomethanes (TTHM) Reduction”
  • NSF/ANSI 58 look for “Trihalomethanes (TTHM) Reduction”
4 compounds tested and not foundBelow the reporting level in every sample. Not found is not the same as zero.
  • Fluoride
  • Lead
  • Nitrate
  • Uranium

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

    Claim: Arsenic (Pentavalent)<=50 ppb Reduction

    For: 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

Moderately hard to hard depending on the source, 120 to 145 mg/L (7 to 8.5 grains per gallon), across 2 sampling points, 2020 to 2024.

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, haloacetic acids (HAA5), chromium (total), total trihalomethanes (TTHM), fluoride, nitrate and uranium results here are California’s own from 2020 on, with EPA’s national file for 2012 to 2019. Rolling Oaks Road Association’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 Sept. 24, 2020 to Dec. 2, 2025.

Testing your own tap

Rolling Oaks Road Association’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 Rolling Oaks Road Association serves, in a straight line. Call first: certification is test by test, and not every lab takes samples from homeowners.

  • Sonoma County Public Health Laboratory

    Santa Rosa, CA · about 4 miles

    Certified for bacteria

    (707) 565-4711

  • K Prime, LLC.

    Santa Rosa, CA · about 6 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 6 miles

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

    (707) 544-8807

All 145 certified labs for California

Sources

PWSID CA4900846. Rebuilt from EPA data on Oct. 18, 2026.

Also in Sonoma County

All California utilities

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