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Town of Duncan

What EPA’s and CDC’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
605 people
Connections
300
Water source
Groundwater
Based in
Duncan, AZ
County
Greenlee
Owner
Local government
The ZIP code it serves

85534

The short answer

2 results are above the health goal. The worst: Uranium, above the health goal. 3 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 1.6 ppm, for the period ending Dec. 31, 2019. None since is on file, so it is not counted as a current finding.

Arsenic, total trihalomethanes (TTHM), nitrate and haloacetic acids (HAA5): Arizona’s yearly averages per water system, as CDC’s Environmental Public Health Tracking Network publishes them, 2020 to 2023, with EPA’s 2012 to 2019 file for earlier years.

Uranium, fluoride and chromium (total): EPA’s compliance monitoring file, samples taken from Dec. 9, 2014 to Feb. 26, 2018. Newer results are in the utility’s annual water quality report.

Above the health goal2

Uranium

Comes from the source

Above the health goal

11.8ppb

Highest yearly average, 2017

Averaged by year, the highest was 11.8 ppb, in 2017: below EPA’s legal limit of 30 ppb, but above its health goal of zero. That is the only year on file.

What handles it

Arsenic

Comes from the source

Above the health goal

2.2ppb

Highest yearly average, 2021 to 2023

Averaged by year, the highest was 2.2 ppb, in 2023: below EPA’s legal limit of 10 ppb, but above its health goal of zero. That was also the latest year on file. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 2.5 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 limits4

Fluoride

Forms or is added in treatment

Below EPA’s limits

2.2ppm

Highest yearly average, 2014 to 2018

2018, one sample: 2.2 ppm

Averaged by year, the highest was 2.2 ppm, in 2014, below EPA’s legal limit of 4.0 ppm. In 2018, the latest year on file, its one sample was 2.2 ppm.

What handles it

Total trihalomethanes (TTHM)

Forms or is added in treatment

Below EPA’s limits

27.3ppb

Highest yearly average, 2021 to 2023

Averaged by year, the highest was 27.3 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 2.1 ppb, in 2012.

What handles it

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

Nitrate

Comes from the source

Below EPA’s limits

2.7ppm

Highest yearly average, 2020 to 2023

2023 average: 1.8 ppm

Averaged by year, the highest was 2.7 ppm, in 2022, below EPA’s legal limit of 10 ppm. In 2023, the latest year on file, it averaged 1.8 ppm. Earlier, from 2012 to 2019, EPA’s file shows a highest sample of 3.7 ppm, in 2014.

What handles it

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

Haloacetic acids (HAA5)

Forms or is added in treatment

Below EPA’s limits

5.9ppb

Highest yearly average, 2021 to 2023

Averaged by year, the highest was 5.9 ppb, in 2023, below EPA’s legal limit of 60 ppb. That was also the latest year on file.

What handles it

No certification claim covers this compound yet.

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

    Claim: Arsenic (Pentavalent)<=50 ppb Reduction

    For: Arsenic

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

  • NSF/ANSI 58

    Claims: Uranium, Arsenic (Pentavalent)<=50 ppb Reduction

    For: Uranium, 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

Violations since 2016

Contaminant or ruleTypePeriodMeasuredStatus
Di(2-ethylhexyl) phthalateThe running average was above the legal limit.EPA: Maximum Contaminant Level Violation, AverageJan. 1, 2025 to March 31, 20250.007 MG/LResolved
Di(2-ethylhexyl) phthalateThe running average was above the legal limit.EPA: Maximum Contaminant Level Violation, AverageOct. 1, 2024 to Dec. 31, 20240.007 MG/LResolved
Groundwater RuleA significant problem found in a state inspection was not fixed on time.EPA: Failure To Address DeficiencyFeb. 11, 2024—Resolved
Health-based violations only. Resolved and archived mean the utility returned to compliance or the state closed the record. 142 monitoring or reporting violations not shown.

What this report can’t tell you

  • Everything else. Arsenic, total trihalomethanes (TTHM), nitrate and haloacetic acids (HAA5) results here are Arizona’s yearly averages as CDC publishes them, from 2020 on, with EPA’s national file for 2012 to 2019. Uranium, fluoride and chromium (total) come from EPA’s file alone, which ends in 2019. Town of Duncan’s own annual report, which it must send you every year, has newer results for those and 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; CDC’s yearly averages for Arizona cover 2020 to 2023; EPA’s compliance samples are from Dec. 9, 2014 to Feb. 26, 2018.

Testing your own tap

Town of Duncan’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 Arizona certifies.

No lab Arizona certifies is within 75 miles of the area Town of Duncan serves on the state’s list. Some take samples by mail; the state’s page lists them all.

All 49 certified labs for Arizona

Sources

PWSID AZ0406001. Rebuilt from EPA data on Oct. 18, 2026.

Towns it serves

Also in Greenlee County

All Arizona utilities

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