Tonto Hills Dwid
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
- 350 people
- Connections
- 150
- Water source
- Surface water bought from another system
- Based in
- Tonto Hills, AZ
- County
- Maricopa
- Owner
- Private
The ZIP code it serves
The short answer
Nothing in EPA’s and CDC’s records for this utility is above a health goal. That covers nitrate, arsenic and other regulated chemicals, plus lead and copper, not everything. No health-based violations on file since 2016.
What was found
Total trihalomethanes (TTHM), haloacetic acids (HAA5) and nitrate: 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.
Below EPA’s limits3
Total trihalomethanes (TTHM)
Forms or is added in treatment
54.4ppb
Highest yearly average, 2020 to 2023
2023 average: 39 ppb
Averaged by year, the highest was 54.4 ppb, in 2021, below EPA’s legal limit of 80 ppb. In 2023, the latest year on file, it averaged 39 ppb. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 71.6 ppb, in 2012.
What handles it
- NSF/ANSI 53 look for “Trihalomethanes (TTHM) Reduction”
- NSF/ANSI 58 look for “Trihalomethanes (TTHM) Reduction”
Haloacetic acids (HAA5)
Forms or is added in treatment
10.1ppb
Highest yearly average, 2020 to 2023
2023 average: 5.0 ppb
Averaged by year, the highest was 10.1 ppb, in 2021, below EPA’s legal limit of 60 ppb. In 2023, the latest year on file, it averaged 5.0 ppb. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 24.7 ppb, in 2012.
What handles it
No certification claim covers this compound yet.
Nitrate
Comes from the source
0.87ppm
Highest yearly average, 2023
Averaged by year, the highest was 0.87 ppm, in 2023, below EPA’s legal limit of 10 ppm. That is the only year on file.
What handles it
- NSF/ANSI 58 look for “Nitrate/Nitrite Reduction”
- NSF/ANSI 53 look for “Nitrate/Nitrite (30 ppm challenge)”
One compound tested and not foundBelow the reporting level in every sample. Not found is not the same as zero.
- Lead
Violations since 2016
No health-based violations on file with EPA since 2016. There are 23 monitoring or reporting violations: a sample missed, late or not reported.
What this report can’t tell you
Everything else. Total trihalomethanes (TTHM), haloacetic acids (HAA5) and nitrate results here are Arizona’s yearly averages as CDC publishes them, from 2020 on, with EPA’s national file for 2012 to 2019. Tonto Hills Dwid’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; CDC’s yearly averages for Arizona cover 2020 to 2023.
Testing your own tap
The 3 labs Arizona certifies closest to the area Tonto Hills Dwid serves, in a straight line. Call first: certification is test by test, and not every lab takes samples from homeowners.
Legend Technical Services of Arizona, Inc. DBA Legend Analytical
Phoenix, AZ · about 25 miles
Motzz Laboratory, Inc.
Phoenix, AZ · about 25 miles
Alliance Technical Group, LLC – Phoenix
Phoenix, AZ · about 25 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 AZ0407076. Rebuilt from EPA data on Oct. 18, 2026.
What to do next
- Nothing here is above a health goalIn EPA’s and CDC’s records for this utility. They don’t cover everything, which is why the next step matters.Every contaminant TapBuff tracks
- Get the utility’s own reportTonto Hills Dwid must send you a water quality report every year. It covers contaminants this page does not show.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
- Decide if you want a filter at allA filter for taste or chlorine is a preference, not a need. The standards say what each kind can do.NSF/ANSI standards, decoded