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Gw Ocotillo Water - Diamond Bell

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
649 people
Connections
264
Water source
Groundwater
Based in
Tucson, AZ
County
Pima
Owner
Local government
The ZIP code it serves

85736

The short answer

2 results are above the health goal. The worst: Arsenic, above the health goal. No health-based violations on file since 2016.

What handles it

What was found

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 Feb. 14, 2013 to March 8, 2019. Newer results are in the utility’s annual water quality report.

Above the health goal2

Arsenic

Comes from the source

Above the health goal

3.6ppb

Highest yearly average, 2022

Averaged by year, the highest was 3.6 ppb, in 2022: below EPA’s legal limit of 10 ppb, but above its health goal of zero. That is the only year on file. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 3.8 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”

Uranium

Comes from the source

Above the health goal

3.4ppb

Highest yearly average, 2013

Averaged by year, the highest was 3.4 ppb, in 2013: 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

Below EPA’s limits5

Total trihalomethanes (TTHM)

Forms or is added in treatment

Below EPA’s limits

20.2ppb

Highest yearly average, 2020 to 2023

2023 average: 11.9 ppb

Averaged by year, the highest was 20.2 ppb, in 2021, below EPA’s legal limit of 80 ppb. In 2023, the latest year on file, it averaged 11.9 ppb. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 35.3 ppb, in 2015.

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

1.6ppm

Highest yearly average, 2020 to 2023

2023 average: 1.6 ppm

Averaged by year, the highest was 1.6 ppm, in 2020, below EPA’s legal limit of 10 ppm. In 2023, the latest year on file, it averaged 1.6 ppm. Earlier, from 2012 to 2019, EPA’s file shows a highest sample of 1.8 ppm, in 2012.

What handles it

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

Fluoride

Forms or is added in treatment

Below EPA’s limits

0.26ppm

Highest yearly average, 2013 to 2019

2019 average: 0.26 ppm

Averaged by year, the highest was 0.26 ppm, in 2013, below EPA’s legal limit of 4.0 ppm. Its highest single sample was 0.31 ppm. In 2019, the latest year on file, its two samples averaged 0.26 ppm.

What handles it

Haloacetic acids (HAA5)

Forms or is added in treatment

Below EPA’s limits

2.6ppb

Highest yearly average, 2020 to 2023

2023 average: 1.3 ppb

Averaged by year, the highest was 2.6 ppb, in 2021, below EPA’s legal limit of 60 ppb. In 2023, the latest year on file, it averaged 1.3 ppb. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 4.5 ppb, in 2015.

What handles it

No certification claim covers this compound yet.

Chromium (total)

Comes from the source

Below EPA’s limits

0.65ppb

Highest yearly average, 2013 to 2019

Averaged by year, the highest was 0.65 ppb, in 2019, below EPA’s legal limit of 100 ppb. Its highest single sample was 1.5 ppb. That was also the latest year on file.

What handles it

One compound tested and not foundBelow the reporting level in every sample. Not found is not the same as zero.
  • 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: Arsenic (Pentavalent)<=50 ppb Reduction, Uranium

    For: Arsenic, Uranium

    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

No health-based violations on file with EPA since 2016.

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. Gw Ocotillo Water - Diamond Bell’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 Feb. 14, 2013 to March 8, 2019.

Testing your own tap

Gw Ocotillo Water - Diamond Bell’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.

The 3 labs Arizona certifies closest to the area Gw Ocotillo Water - Diamond Bell serves, in a straight line. Call first: certification is test by test, and not every lab takes samples from homeowners.

  • Turner Laboratories, Inc.

    Tucson, AZ · about 34 miles

    (520) 882-5880

  • Complete Analytical Services, LLC

    Tucson, AZ · about 34 miles

    (520) 884-5811

  • Legend Technical Services of Arizona, Inc. DBA Legend Analytical

    Tucson, AZ · about 34 miles

    (520) 327-1234

All 49 certified labs for Arizona

Sources

PWSID AZ0410159. Rebuilt from EPA data on Oct. 18, 2026.

Towns it serves

Also in Pima County

All Arizona utilities

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