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Konocti Shores

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
30 people
Connections
99
Water source
Groundwater
Based in
Orinda, CA
County
Lake
Owner
Private
Hardness
Hard
The ZIP code it serves

95451

The short answer

1 result is above EPA’s legal limit, and 2 more are above the health goal. The worst: Copper, above the action level. No health-based violations on file since 2016.

What handles it

What was found

Lead and copper: EPA SDWIS monitoring periods ending 2022.

Nitrate, arsenic, fluoride, haloacetic acids (HAA5), total trihalomethanes (TTHM) and chromium (total): California’s own results, samples taken from Jan. 17, 2020 to June 10, 2026, with EPA’s 2012 to 2019 file for earlier years.

Above the legal limit1

Copper

Comes from pipes, often your own

Above the action level

1.7ppm

90th percentile, 2020 to 2022

In the latest period, 9 in 10 homes sampled were at or below 1.7 ppm, above EPA’s action level of 1.3 ppm.

What handles it

Above the health goal2

Nitrate

Comes from the source

Above the health goal

36ppm

Highest sample; found in 92 of 94

2026 average: 9.1 ppm

From 2025 to 2026, five samples were above EPA’s legal limit of 10 ppm, the highest 36 ppm in 2026. The next sample at the same point, within 30 days, kept the average above the limit for four; one has no follow-up sample on file within 30 days. 10 ppm is also EPA’s health goal. That was also the latest year on file, and its 10 samples averaged 9.1 ppm. EPA recorded no violation for nitrate at this utility since 2020. Earlier, from 2012 to 2019, EPA’s file shows a highest sample of 9.0 ppm, in 2019.

What handles it

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

Arsenic

Comes from the source

Above the health goal

2.9ppb

Highest yearly average, 2022 to 2025

Averaged by year, the highest was 2.9 ppb, in 2025: below EPA’s legal limit of 10 ppb, but above its health goal of zero. Its highest single sample was 3.5 ppb. That was also the latest year on file. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 4.2 ppb, in 2016.

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

Fluoride

Forms or is added in treatment

Below EPA’s limits

0.17ppm

Highest yearly average, 2022 to 2025

Averaged by year, the highest was 0.17 ppm, in 2025, below EPA’s legal limit of 4.0 ppm. Its highest single sample was 0.18 ppm. That was also the latest year on file. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 0.2 ppm, in 2016.

What handles it

Haloacetic acids (HAA5)

Forms or is added in treatment

Below EPA’s limits

2.1ppb

Highest yearly average, 2020 to 2023

2023, one sample: 1.6 ppb

Averaged by year, the highest was 2.1 ppb, in 2020, below EPA’s legal limit of 60 ppb. In 2023, the latest year on file, its one sample was 1.6 ppb. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 0.5 ppb, in 2017.

What handles it

No certification claim covers this compound yet.

Total trihalomethanes (TTHM)

Forms or is added in treatment

Below EPA’s limits

2.8ppb

Highest yearly average, 2020 to 2023

Averaged by year, the highest was 2.8 ppb, in 2023, 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 2.2 ppb, in 2017.

What handles it

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

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, Nitrate/Nitrite (30 ppm challenge), Arsenic (Pentavalent)<=50 ppb Reduction

    For: Copper, Nitrate, Arsenic

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

  • NSF/ANSI 58

    Claims: Copper Reduction, Nitrate/Nitrite Reduction, Arsenic (Pentavalent)<=50 ppb Reduction

    For: Copper, Nitrate, Arsenic

    Other certifiers’ wording: Nitrate; 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

Hardness

Hard, typically 135 mg/L (7.9 grains per gallon), across 2 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 at 7.9 grains per gallon, 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. There are 2 monitoring or reporting violations: a sample missed, late or not reported.

What this report can’t tell you

  • Everything else. Nitrate, arsenic, fluoride, haloacetic acids (HAA5), total trihalomethanes (TTHM) and chromium (total) results here are California’s own from 2020 on, with EPA’s national file for 2012 to 2019. Konocti Shores’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. 17, 2020 to June 10, 2026.

Testing your own tap

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

  • Alpha Analytical Laboratories, Inc. - Ukiah

    Ukiah, CA · about 27 miles

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

    (707) 468-0401

  • K Prime, LLC.

    Santa Rosa, CA · about 29 miles

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

    (707) 527-7574

  • Sonoma County Public Health Laboratory

    Santa Rosa, CA · about 32 miles

    Certified for bacteria

    (707) 565-4711

All 145 certified labs for California

Sources

PWSID CA1700592. Rebuilt from EPA data on Oct. 18, 2026.

Also in Lake County

All California utilities

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