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Nicasio Valley Ranch Mutual

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
36 people
Connections
14
Water source
Groundwater
Based in
Nicasio, CA
County
Marin
Owner
Private
Hardness
Very hard
The ZIP code it serves

94946

The short answer

2 results are above EPA’s legal limit, 1 more is above the limit’s level with no violation recorded, and 1 more is above the health goal. The worst: Copper, above the action level. 6 health-based violations since 2016.

What handles it

What was found

Lead and copper: EPA SDWIS monitoring periods ending 2012 to 2024.

Total trihalomethanes (TTHM), arsenic, haloacetic acids (HAA5), fluoride, nitrate and chromium (total): California’s own results, samples taken from Jan. 2, 2020 to June 11, 2026, with EPA’s 2012 to 2019 file for earlier years.

Above the legal limit2

Copper

Comes from pipes, often your own

Above the action level

1.8ppm

90th percentile, 2022 to 2024

In the latest period, 9 in 10 homes sampled were at or below 1.8 ppm, above EPA’s action level of 1.3 ppm.

What handles it

Total trihalomethanes (TTHM)

Forms or is added in treatment

Above the legal limit

51.8ppb

Highest yearly average, 2020 to 2026

2026 average: 13.4 ppb

Averaged by year, the highest was 51.8 ppb, in 2022, below EPA’s legal limit of 80 ppb. Its highest single sample was 121 ppb. In 2026, the latest year on file, its five samples averaged 13.4 ppb. EPA judges this limit at each sampling point, and recorded a violation for total trihalomethanes (TTHM) at this utility in 2021. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 101 ppb, in 2015, and EPA recorded violations in 2015, 2017, 2018 and 2019.

What handles it

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

Above the limit’s level, no violation recorded1

Arsenic

Comes from the source

Above the limit’s level, no violation

20.7ppb

Highest yearly average, 2020 to 2026

Averaged by year, the highest was 20.7 ppb, in 2026, about twice EPA’s legal limit of 10 ppb. Its highest single sample was 82 ppb. That was also the latest year on file. 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 24.3 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”

Above the health goal1

Lead

Comes from pipes, often your own

Above the health goal

4.0ppb

90th percentile, 2022 to 2024

In the latest period, 9 in 10 homes sampled were at or below 4.0 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

Below EPA’s limits3

Haloacetic acids (HAA5)

Forms or is added in treatment

Below EPA’s limits

11.5ppb

Highest yearly average, 2020 to 2026

2026 average: 8.4 ppb

Averaged by year, the highest was 11.5 ppb, in 2022, below EPA’s legal limit of 60 ppb. Its highest single sample was 54.7 ppb. In 2026, the latest year on file, its seven samples averaged 8.4 ppb. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 41.6 ppb, in 2012.

What handles it

No certification claim covers this compound yet.

Fluoride

Forms or is added in treatment

Below EPA’s limits

0.4ppm

Highest yearly average, 2020 to 2026

2026, one sample: 0.24 ppm

Averaged by year, the highest was 0.4 ppm, in 2021, below EPA’s legal limit of 4.0 ppm. In 2026, the latest year on file, its one sample was 0.24 ppm. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 0.46 ppm, in 2012.

What handles it

Nitrate

Comes from the source

Below EPA’s limits

0.42ppm

Highest sample; found in 1 of 14

2026: not found

The highest sample, in 2023, was 0.42 ppm, below EPA’s legal limit of 10 ppm. In 2026, the latest year on file, it wasn’t found in its one sample.

What handles it

  • NSF/ANSI 58 look for “Nitrate/Nitrite Reduction”
  • NSF/ANSI 53 look for “Nitrate/Nitrite (30 ppm challenge)”
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: Copper Reduction, Trihalomethanes (TTHM) Reduction, Arsenic (Pentavalent)<=50 ppb Reduction, Lead Reduction

    For: Copper, Total trihalomethanes (TTHM), Arsenic, Lead

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

  • NSF/ANSI 58

    Claims: Copper Reduction, Trihalomethanes (TTHM) Reduction, Arsenic (Pentavalent)<=50 ppb Reduction, Lead Reduction

    For: Copper, Total trihalomethanes (TTHM), Arsenic, 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

Very hard, typically 193 mg/L (11.3 grains per gallon), across 2 sampling points, 2020 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 at 11.3 grains per gallon, salt includedSoftener or salt-free conditioner?California water hardness, utility by utility

Violations since 2016

Contaminant or ruleTypePeriodMeasuredStatus
TTHMThe running average was above the legal limit.EPA: Maximum Contaminant Level Violation, AverageOct. 1, 2021 to Dec. 31, 20210.096 MG/LResolved
TTHMThe running average was above the legal limit.EPA: Maximum Contaminant Level Violation, AverageJuly 1, 2019 to Sept. 30, 2019140 UG/LResolved
TTHMThe running average was above the legal limit.EPA: Maximum Contaminant Level Violation, AverageApril 1, 2019 to June 30, 201981 UG/LResolved
TTHMThe running average was above the legal limit.EPA: Maximum Contaminant Level Violation, AverageOct. 1, 2018 to Dec. 31, 201889 UG/LResolved
TTHMThe running average was above the legal limit.EPA: Maximum Contaminant Level Violation, AverageJuly 1, 2018 to Sept. 30, 201898 UG/LResolved
TTHMThe running average was above the legal limit.EPA: Maximum Contaminant Level Violation, AverageOct. 1, 2017 to Dec. 31, 2017130 UG/LResolved
Health-based violations only. Resolved and archived mean the utility returned to compliance or the state closed the record. 3 monitoring or reporting violations not shown.

What this report can’t tell you

  • Everything else. Total trihalomethanes (TTHM), arsenic, haloacetic acids (HAA5), fluoride, nitrate and chromium (total) results here are California’s own from 2020 on, with EPA’s national file for 2012 to 2019. Nicasio Valley Ranch Mutual’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. 2, 2020 to June 11, 2026.

Testing your own tap

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

  • Alpha Analytical Laboratories Inc. - North Bay

    Petaluma, CA · about 13 miles

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

    (707) 769-3128

  • Brelje and Race Laboratories, Inc.

    Santa Rosa, CA · about 25 miles

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

    (707) 544-8807

  • Cel Analytical, Inc.

    San Francisco, CA · about 26 miles

    Certified for bacteria, minerals and other inorganics

    (415) 882-1690

All 145 certified labs for California

Sources

PWSID CA2100579. Rebuilt from EPA data on Oct. 18, 2026.

Also in Marin County

All California utilities

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