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Milton Road Water Company

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
39 people
Connections
24
Water source
Groundwater
Based in
Napa, CA
County
Napa
Owner
Private
Hardness
Very hard
The ZIP code it serves

94559

The short answer

1 result is above the health goal. The worst: Arsenic, above the health goal. 2 health-based violations since 2016.

What handles it

What was found

Copper: EPA’s file records a utility’s copper only when it exceeds the action level. The last here was 2.4 ppm, for the period ending Dec. 31, 2011. None since is on file, so it is not counted as a current finding.

Arsenic, chromium (total), fluoride and nitrate: California’s own results, samples taken from June 1, 2020 to Nov. 12, 2025, with EPA’s 2012 to 2019 file for earlier years.

Above the health goal1

Arsenic

Comes from the source

Above the health goal

6.5ppb

Highest yearly average, 2021 to 2024

2024, one sample: 4.4 ppb

Averaged by year, the highest was 6.5 ppb, in 2021: below EPA’s legal limit of 10 ppb, but above its health goal of zero. In 2024, the latest year on file, its one sample was 4.4 ppb. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 5.3 ppb, in 2012.

What handles it

  • NSF/ANSI 58 look for “Arsenic (Pentavalent)<=50 ppb Reduction”
  • NSF/ANSI 53 look for “Arsenic (Pentavalent)<=50 ppb Reduction”
4 compounds tested and not foundBelow the reporting level in every sample. Not found is not the same as zero.
  • Chromium (total)
  • Fluoride
  • 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

Very hard, 932 mg/L (54.5 grains per gallon), at its one sampling point, 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 54.5 grains per gallon, salt includedSoftener or salt-free conditioner?California water hardness, utility by utility

Violations since 2016

Contaminant or ruleTypePeriodMeasuredStatus
Lead and Copper Rule RevisionsThe required inventory of lead service lines was not completed or submitted on time.EPA: LSL InventoryOct. 17, 2024—Unaddressed
Coliform (TCR)Too many samples in a month tested positive for coliform bacteria.EPA: Maximum Contaminant Level Violation, Monthly (TCR)Jan. 1, 2016 to Jan. 31, 2016—Archived
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. Arsenic, chromium (total), fluoride and nitrate results here are California’s own from 2020 on, with EPA’s national file for 2012 to 2019. Milton Road Water Company’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 June 1, 2020 to Nov. 12, 2025.

Testing your own tap

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

  • Caltest Analytical Laboratory

    Napa, CA · about 3 miles

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

    (707) 258-4000

  • Napa-Solano-Yolo-Marin Public Health Laboratory

    Fairfield, CA · about 13 miles

    Certified for bacteria

    (707) 784-4410

  • Alpha Analytical Laboratories Inc. - North Bay

    Petaluma, CA · about 19 miles

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

    (707) 769-3128

All 145 certified labs for California

Sources

PWSID CA2801080. Rebuilt from EPA data on Oct. 18, 2026.

Towns it serves

Also in Napa County

All California utilities

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