White Horse Ranch Owners Association
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
- 292 people
- Connections
- 171
- Water source
- Groundwater
- Based in
- Dewey, AZ
- County
- Yavapai
- Owner
- Public and private
The ZIP code it serves
The short answer
1 result is above EPA’s legal limit, and 2 more are above the health goal. The worst: Nitrate, above the legal limit. 37 health-based violations since 2016.
What handles itWhat was found
Nitrate, uranium, total trihalomethanes (TTHM) 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.
Arsenic, fluoride and chromium (total): EPA’s compliance monitoring file, samples taken from Oct. 24, 2016 to Oct. 24, 2016. Newer results are in the utility’s annual water quality report.
Above the legal limit1
Nitrate
Comes from the source
15.7ppm
Highest yearly average, 2020 to 2023
Averaged by year, the highest was 15.7 ppm, in 2023, above EPA’s legal limit of 10 ppm. That was also the latest year on file. EPA recorded violations for nitrate at this utility in 2020, 2021, 2022, 2023, 2024, 2025 and 2026. Earlier, from 2012 to 2019, EPA’s file shows a highest sample of 18 ppm, in 2018, and EPA recorded violations in 2015, 2016, 2017, 2018 and 2019.
What handles it
- NSF/ANSI 58 look for “Nitrate/Nitrite Reduction”
- NSF/ANSI 53 look for “Nitrate/Nitrite (30 ppm challenge)”
Above the health goal2
Uranium
Comes from the source
26.3ppb
Highest yearly average, 2022 to 2023
2023 average: 23.3 ppb
Averaged by year, the highest was 26.3 ppb, in 2022: below EPA’s legal limit of 30 ppb, but above its health goal of zero. In 2023, the latest year on file, it averaged 23.3 ppb. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 23 ppb, in 2019.
What handles it
- NSF/ANSI 58 look for “Uranium”
Arsenic
Comes from the source
4.5ppb
Highest yearly average, 2016
Averaged by year, the highest was 4.5 ppb, in 2016: below EPA’s legal limit of 10 ppb, but above its health goal of zero. That is the only year on file.
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
Total trihalomethanes (TTHM)
Forms or is added in treatment
42.4ppb
Highest yearly average, 2020 to 2023
2023 average: 27.8 ppb
Averaged by year, the highest was 42.4 ppb, in 2021, below EPA’s legal limit of 80 ppb. In 2023, the latest year on file, it averaged 27.8 ppb. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 49.2 ppb, in 2017.
What handles it
- NSF/ANSI 53 look for “Trihalomethanes (TTHM) Reduction”
- NSF/ANSI 58 look for “Trihalomethanes (TTHM) Reduction”
Fluoride
Forms or is added in treatment
0.64ppm
Highest yearly average, 2016
Averaged by year, the highest was 0.64 ppm, in 2016, below EPA’s legal limit of 4.0 ppm. That is the only year on file.
What handles it
- NSF/ANSI 58 look for “Fluoride Reduction”
- NSF/ANSI 53 look for “Fluoride”
Haloacetic acids (HAA5)
Forms or is added in treatment
6.6ppb
Highest yearly average, 2020 to 2023
2023 average: 4.3 ppb
Averaged by year, the highest was 6.6 ppb, in 2021, below EPA’s legal limit of 60 ppb. In 2023, the latest year on file, it averaged 4.3 ppb. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 18 ppb, in 2013.
What handles it
No certification claim covers this compound yet.
Chromium (total)
Comes from the source
1.6ppb
Highest yearly average, 2016
Averaged by year, the highest was 1.6 ppb, in 2016, below EPA’s legal limit of 100 ppb. That is the only year on file.
What handles it
- NSF/ANSI 58 look for “Chromium (Hexavalent) Reduction”
- NSF/ANSI 53 look for “Chromium Reduction”
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
Claims: Nitrate/Nitrite (30 ppm challenge), Arsenic (Pentavalent)<=50 ppb Reduction
For: Nitrate, Arsenic
Other certifiers’ wording: Arsenic (III) (50 ppb influent level)
- NSF/ANSI 58
Claims: Nitrate/Nitrite Reduction, Uranium, Arsenic (Pentavalent)<=50 ppb Reduction
For: Nitrate, Uranium, Arsenic
Other certifiers’ wording: Nitrate; 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
Countertop reverse osmosis
- IAPMO listing:NSF/ANSI 42NSF/ANSI 53NSF/ANSI 58NSF/ANSI 401checked Oct. 4, 2026
Certified for: Nitrate, Arsenic
Aquasana SmartFlow Reverse Osmosis (AQ-SFRO2)
Under-sink reverse osmosis
- WQA listing:NSF/ANSI 42NSF/ANSI 53NSF/ANSI 58NSF/ANSI 401checked Oct. 9, 2026
Certified for: Nitrate, Arsenic
Culligan 10-Cup Pitcher with ZeroWater Technology (ZEROP10)
Pitcher
- IAPMO listing:NSF/ANSI 42NSF/ANSI 53NSF/ANSI 401checked Oct. 9, 2026
Certified for: Nitrate
Brondell Capella RC250 Reverse Osmosis System
Under-sink reverse osmosis
- WQA listing:NSF/ANSI 42NSF/ANSI 53NSF/ANSI 58NSF/ANSI 401checked Oct. 9, 2026
Certified for: Arsenic
Violations since 2016
| Contaminant or rule | Type | Period | Measured | Status |
|---|---|---|---|---|
| Nitrate | A sample was above the legal limit, for a contaminant judged one sample at a time.EPA: Maximum Contaminant Level Violation, Single Sample | April 1, 2026 to June 30, 2026 | 20 MG/L | Archived |
| Nitrate | A sample was above the legal limit, for a contaminant judged one sample at a time.EPA: Maximum Contaminant Level Violation, Single Sample | Jan. 1, 2026 to March 31, 2026 | 23 MG/L | Archived |
| Groundwater Rule | A significant problem found in a state inspection was not fixed on time.EPA: Failure To Address Deficiency | Nov. 6, 2025 | — | Unaddressed |
| Groundwater Rule | A significant problem found in a state inspection was not fixed on time.EPA: Failure To Address Deficiency | Nov. 6, 2025 | — | Unaddressed |
| Nitrate | A sample was above the legal limit, for a contaminant judged one sample at a time.EPA: Maximum Contaminant Level Violation, Single Sample | Oct. 1, 2025 to Dec. 31, 2025 | 23 MG/L | Archived |
| Nitrate | A sample was above the legal limit, for a contaminant judged one sample at a time.EPA: Maximum Contaminant Level Violation, Single Sample | July 1, 2025 to Sept. 30, 2025 | 24 MG/L | Archived |
| Nitrate | A sample was above the legal limit, for a contaminant judged one sample at a time.EPA: Maximum Contaminant Level Violation, Single Sample | April 1, 2025 to June 30, 2025 | 22 MG/L | Archived |
| Nitrate | A sample was above the legal limit, for a contaminant judged one sample at a time.EPA: Maximum Contaminant Level Violation, Single Sample | Jan. 1, 2025 to March 31, 2025 | 19 MG/L | Archived |
| Nitrate | A sample was above the legal limit, for a contaminant judged one sample at a time.EPA: Maximum Contaminant Level Violation, Single Sample | Oct. 1, 2024 to Dec. 31, 2024 | 12 MG/L | Archived |
| Nitrate | A sample was above the legal limit, for a contaminant judged one sample at a time.EPA: Maximum Contaminant Level Violation, Single Sample | July 1, 2024 to Sept. 30, 2024 | 17 MG/L | Archived |
| Nitrate | A sample was above the legal limit, for a contaminant judged one sample at a time.EPA: Maximum Contaminant Level Violation, Single Sample | April 1, 2024 to June 30, 2024 | 15 MG/L | Archived |
| Nitrate | A sample was above the legal limit, for a contaminant judged one sample at a time.EPA: Maximum Contaminant Level Violation, Single Sample | Jan. 1, 2024 to March 31, 2024 | 14 MG/L | Archived |
| Nitrate | A sample was above the legal limit, for a contaminant judged one sample at a time.EPA: Maximum Contaminant Level Violation, Single Sample | Oct. 1, 2023 to Dec. 31, 2023 | 12 MG/L | Archived |
| Nitrate | A sample was above the legal limit, for a contaminant judged one sample at a time.EPA: Maximum Contaminant Level Violation, Single Sample | July 1, 2023 to Sept. 30, 2023 | 18 MG/L | Archived |
| Nitrate | A sample was above the legal limit, for a contaminant judged one sample at a time.EPA: Maximum Contaminant Level Violation, Single Sample | April 1, 2023 to June 30, 2023 | 14 MG/L | Archived |
| Nitrate | A sample was above the legal limit, for a contaminant judged one sample at a time.EPA: Maximum Contaminant Level Violation, Single Sample | Jan. 1, 2023 to March 31, 2023 | 15 MG/L | Archived |
| Nitrate | A sample was above the legal limit, for a contaminant judged one sample at a time.EPA: Maximum Contaminant Level Violation, Single Sample | Oct. 1, 2022 to Dec. 31, 2022 | 14 MG/L | Archived |
| Nitrate | A sample was above the legal limit, for a contaminant judged one sample at a time.EPA: Maximum Contaminant Level Violation, Single Sample | July 1, 2022 to Sept. 30, 2022 | 13 MG/L | Archived |
| Nitrate | A sample was above the legal limit, for a contaminant judged one sample at a time.EPA: Maximum Contaminant Level Violation, Single Sample | April 1, 2022 to June 30, 2022 | 13 MG/L | Archived |
| Nitrate | A sample was above the legal limit, for a contaminant judged one sample at a time.EPA: Maximum Contaminant Level Violation, Single Sample | Jan. 1, 2022 to March 31, 2022 | 12 MG/L | Archived |
| Nitrate | A sample was above the legal limit, for a contaminant judged one sample at a time.EPA: Maximum Contaminant Level Violation, Single Sample | Oct. 1, 2021 to Dec. 31, 2021 | 10.6 MG/L | Archived |
| Nitrate | A sample was above the legal limit, for a contaminant judged one sample at a time.EPA: Maximum Contaminant Level Violation, Single Sample | April 1, 2021 to June 30, 2021 | 14 MG/L | Archived |
| Nitrate | The running average was above the legal limit.EPA: Maximum Contaminant Level Violation, Average | April 1, 2021 to June 30, 2021 | 14 MG/L | Archived |
| Nitrate | A sample was above the legal limit, for a contaminant judged one sample at a time.EPA: Maximum Contaminant Level Violation, Single Sample | Oct. 1, 2020 to Dec. 31, 2020 | 11 MG/L | Archived |
| Nitrate | A sample was above the legal limit, for a contaminant judged one sample at a time.EPA: Maximum Contaminant Level Violation, Single Sample | July 1, 2020 to Sept. 30, 2020 | 14 MG/L | Resolved |
| Nitrate | A sample was above the legal limit, for a contaminant judged one sample at a time.EPA: Maximum Contaminant Level Violation, Single Sample | April 1, 2020 to June 30, 2020 | 12 MG/L | Resolved |
| Nitrate | The running average was above the legal limit.EPA: Maximum Contaminant Level Violation, Average | Jan. 1, 2020 to March 31, 2020 | 15 MG/L | Resolved |
| Nitrate | A sample was above the legal limit, for a contaminant judged one sample at a time.EPA: Maximum Contaminant Level Violation, Single Sample | Oct. 1, 2019 to Dec. 31, 2019 | 12 MG/L | Resolved |
| Nitrate | A sample was above the legal limit, for a contaminant judged one sample at a time.EPA: Maximum Contaminant Level Violation, Single Sample | April 1, 2019 to June 30, 2019 | 11 MG/L | Resolved |
| Nitrate | A sample was above the legal limit, for a contaminant judged one sample at a time.EPA: Maximum Contaminant Level Violation, Single Sample | July 1, 2018 to Sept. 30, 2018 | 12 MG/L | Resolved |
| Nitrate | A sample was above the legal limit, for a contaminant judged one sample at a time.EPA: Maximum Contaminant Level Violation, Single Sample | April 1, 2018 to June 30, 2018 | 12 MG/L | Resolved |
| Nitrate | The running average was above the legal limit.EPA: Maximum Contaminant Level Violation, Average | Jan. 1, 2018 to March 31, 2018 | 15 MG/L | Resolved |
| Nitrate | A sample was above the legal limit, for a contaminant judged one sample at a time.EPA: Maximum Contaminant Level Violation, Single Sample | Oct. 1, 2017 to Dec. 31, 2017 | 11 MG/L | Resolved |
| Nitrate | The running average was above the legal limit.EPA: Maximum Contaminant Level Violation, Average | July 1, 2017 to Sept. 30, 2017 | 16 MG/L | Resolved |
| Nitrate | A sample was above the legal limit, for a contaminant judged one sample at a time.EPA: Maximum Contaminant Level Violation, Single Sample | April 1, 2017 to June 30, 2017 | 16 MG/L | Resolved |
| Nitrate | A sample was above the legal limit, for a contaminant judged one sample at a time.EPA: Maximum Contaminant Level Violation, Single Sample | Jan. 1, 2017 to March 31, 2017 | 13 MG/L | Resolved |
| Nitrate | A sample was above the legal limit, for a contaminant judged one sample at a time.EPA: Maximum Contaminant Level Violation, Single Sample | Jan. 1, 2016 to March 31, 2016 | 11 MG/L | Resolved |
| Health-based violations only. Resolved and archived mean the utility returned to compliance or the state closed the record. 8 monitoring or reporting violations not shown. | ||||
What this report can’t tell you
Everything else. Nitrate, uranium, total trihalomethanes (TTHM) 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. Arsenic, fluoride and chromium (total) come from EPA’s file alone, which ends in 2019. White Horse Ranch Owners Association’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 Oct. 24, 2016 to Oct. 24, 2016.
Testing your own tap
The 3 labs Arizona certifies closest to the area White Horse Ranch Owners Association serves, in a straight line. Call first: certification is test by test, and not every lab takes samples from homeowners.
Bradshaw Mountain Environmental Inc.
Prescott Valley, AZ · about 8 miles
Inner Basin Environmental, LLC
Flagstaff, AZ · about 58 miles
Nortest Analytical
Flagstaff, AZ · about 58 miles
Sources
- EPA UCMR 5 occurrence data, file of Oct. 15, 2026
- EPA SDWA bulk download (SDWIS federal data), 2026 Q3
- CDC Environmental Public Health Tracking Network, yearly averages Arizona supplied to CDC, 2020 to 2023, read Oct. 8, 2026. TapBuff’s comparisons with EPA’s limits are its own, not CDC’s or Arizona’s.
- EPA Six-Year Review 4 compliance monitoring data, 2012 to 2019, file of Feb. 5, 2024
- Certified labs: Arizona Department of Health Services, Arizona certified commercial drinking water laboratories, read Oct. 17, 2026; distances from the Census 2020 ZIP code tabulation area gazetteer
- Limits and goals: each contaminant’s page, with its EPA source.
- How this page is built: methodology.
PWSID AZ0413221. Rebuilt from EPA data on Oct. 18, 2026.
What to do next
- Read up on the 3 results above a lineWhat each one does to health, where it comes from, and the certification claim that addresses it.Start with Nitrate
- Get the utility’s own reportWhite Horse Ranch Owners Association must send you a water quality report every year. It covers contaminants this page does not show, and has newer results than EPA’s national file for the ones here that come from it.How to read it
- Test your own tap for leadYour service line, solder and fixtures decide the lead at your faucet, not the utility’s average.Lead in your water: what to do
- Compare certified filtersWhat the filters certified for these results cost over five years, cartridges included.Compare five-year costs