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Doubletree Ranch Water System

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
66 people
Connections
20
Water source
Groundwater
Based in
Livermore, CA
County
Contra Costa
Owner
Private
Hardness
Soft
The ZIP code it serves

94551

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. 10 health-based violations since 2016.

What handles it

What was found

Arsenic, fluoride, chromium (total) and nitrate: California’s own results, samples taken from March 17, 2020 to June 6, 2026, 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

43ppb

Highest yearly average, 2020 to 2026

2026 average: 37.3 ppb

Averaged by year, the highest was 43 ppb, in 2025, about 4.3 times EPA’s legal limit of 10 ppb. Its highest single sample was 50 ppb. In 2026, the latest year on file, its three samples averaged 37.3 ppb, above the limit. 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 40.2 ppb, in 2019, and EPA recorded violations in 2013, 2014, 2015, 2016, 2017 and 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 limits1

Fluoride

Forms or is added in treatment

Below EPA’s limits

0.81ppm

Highest yearly average, 2020 to 2024

2024 average: 0.72 ppm

Averaged by year, the highest was 0.81 ppm, in 2020, below EPA’s legal limit of 4.0 ppm. Its highest single sample was 0.86 ppm. In 2024, the latest year on file, its two samples averaged 0.72 ppm. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 0.69 ppm, in 2017.

What handles it

3 compounds tested and not foundBelow the reporting level in every sample. Not found is not the same as zero.
  • Chromium (total)
  • Lead
  • Nitrate

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

Soft, typically 7 mg/L (0.4 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 at 0.4 grains per gallon, salt includedSoftener or salt-free conditioner?California water hardness, utility by utility

Violations since 2016

Contaminant or ruleTypePeriodMeasuredStatus
ArsenicThe running average was above the legal limit.EPA: Maximum Contaminant Level Violation, AverageApril 1, 2018 to June 30, 201833 UG/LResolved
ArsenicThe running average was above the legal limit.EPA: Maximum Contaminant Level Violation, AverageJan. 1, 2018 to March 31, 201833 UG/LResolved
ArsenicThe running average was above the legal limit.EPA: Maximum Contaminant Level Violation, AverageOct. 1, 2017 to Dec. 31, 201738 UG/LResolved
ArsenicThe running average was above the legal limit.EPA: Maximum Contaminant Level Violation, AverageJuly 1, 2017 to Sept. 30, 201734 UG/LResolved
ArsenicThe running average was above the legal limit.EPA: Maximum Contaminant Level Violation, AverageApril 1, 2017 to June 30, 20170.028 UG/LResolved
ArsenicThe running average was above the legal limit.EPA: Maximum Contaminant Level Violation, AverageJan. 1, 2017 to March 31, 201728.5 UG/LResolved
ArsenicThe running average was above the legal limit.EPA: Maximum Contaminant Level Violation, AverageOct. 1, 2016 to Dec. 31, 20160.026 MG/LResolved
ArsenicThe running average was above the legal limit.EPA: Maximum Contaminant Level Violation, AverageJuly 1, 2016 to Sept. 30, 20160.028 MG/LResolved
ArsenicThe running average was above the legal limit.EPA: Maximum Contaminant Level Violation, AverageMarch 1, 2016 to June 30, 20160.027 MG/LResolved
ArsenicThe running average was above the legal limit.EPA: Maximum Contaminant Level Violation, AverageJan. 1, 2016 to March 31, 20160.022 MG/LResolved
Health-based violations only. Resolved and archived mean the utility returned to compliance or the state closed the record. 1 monitoring or reporting violation not shown.

What this report can’t tell you

  • Everything else. Arsenic, fluoride, chromium (total) and nitrate results here are California’s own from 2020 on, with EPA’s national file for 2012 to 2019. Doubletree Ranch Water System’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 March 17, 2020 to June 6, 2026.

Testing your own tap

Doubletree Ranch Water System’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 Doubletree Ranch Water System 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 9 miles

    Certified for bacteria

    (707) 769-3128

  • AEMTEK, Inc

    Fremont, CA · about 20 miles

    Certified for bacteria, minerals and other inorganics

    (510) 979-1979

  • McCampbell Analytical, Inc.

    Pittsburg, CA · about 21 miles

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

    (925) 252-9262

All 145 certified labs for California

Sources

PWSID CA0707615. Rebuilt from EPA data on Oct. 18, 2026.

Towns it serves

Also in Contra Costa County

All California utilities

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