Stony Hills Water System

What EPA’s and Texas’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: 723 people
Connections: 241
Water source: Groundwater
Based in: Austin, TX
County: Denton
Owner: Private

The ZIP code it serves

76259

The short answer

Nothing in EPA’s and Texas’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

Haloacetic acids (HAA5), total trihalomethanes (TTHM), chromium (total), fluoride, nitrate, arsenic and uranium: Texas’s own results, samples taken from Nov. 5, 2020 to June 16, 2026, with EPA’s 2012 to 2019 file for earlier years.

Below EPA’s limits5

Haloacetic acids (HAA5)

Forms or is added in treatment

Below EPA’s limits

4.2ppb

Highest yearly average, 2022 to 2026

2026: not found

Averaged by year, the highest was 4.2 ppb, in 2023, below EPA’s legal limit of 60 ppb. In 2026, the latest year on file, it wasn’t found in its one sample.

What handles it

No certification claim covers this compound yet.

Total trihalomethanes (TTHM)

Forms or is added in treatment

Below EPA’s limits

5.2ppb

Highest yearly average, 2022 to 2026

2026, one sample: 4.3 ppb

Averaged by year, the highest was 5.2 ppb, in 2022, below EPA’s legal limit of 80 ppb. In 2026, the latest year on file, its one sample was 4.3 ppb. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 4.9 ppb, in 2013.

What handles it

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

Chromium (total)

Comes from the source

Below EPA’s limits

3.5ppb

Highest yearly average, 2021 to 2024

2024: not found

Averaged by year, the highest was 3.5 ppb, in 2021, below EPA’s legal limit of 100 ppb. Its highest single sample was 3.9 ppb. In 2024, the latest year on file, it wasn’t found in any of its two samples. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 4.8 ppb, in 2012.

What handles it

NSF/ANSI 58 look for “Chromium (Hexavalent) Reduction”
NSF/ANSI 53 look for “Chromium Reduction”

Fluoride

Forms or is added in treatment

Below EPA’s limits

0.14ppm

Highest yearly average, 2021 to 2024

2024 average: 0.12 ppm

Averaged by year, the highest was 0.14 ppm, in 2021, below EPA’s legal limit of 4.0 ppm. Its highest single sample was 0.15 ppm. In 2024, the latest year on file, its two samples averaged 0.12 ppm. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 0.24 ppm, in 2012.

What handles it

NSF/ANSI 58 look for “Fluoride Reduction”
NSF/ANSI 53 look for “Fluoride”

Nitrate

Comes from the source

Below EPA’s limits

0.18ppm

Highest sample; found in 13 of 13

2026 average: 0.12 ppm

The highest sample, in 2026, was 0.18 ppm, below EPA’s legal limit of 10 ppm. That was also the latest year on file, and its two samples averaged 0.12 ppm. Earlier, from 2012 to 2019, EPA’s file shows a highest sample of 0.061 ppm, in 2014.

What handles it

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

3 compounds tested and not foundBelow the reporting level in every sample. Not found is not the same as zero.

Arsenic
Lead
Uranium

Violations since 2016

No health-based violations on file with EPA since 2016. There are 9 monitoring or reporting violations: a sample missed, late or not reported.

What this report can’t tell you

Everything else. Haloacetic acids (HAA5), total trihalomethanes (TTHM), chromium (total), fluoride, nitrate, arsenic and uranium results here are Texas’s own from 2020 on, with EPA’s national file for 2012 to 2019. Stony Hills Water System’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; Texas’s results run from Nov. 5, 2020 to June 16, 2026.

Testing your own tap

Stony Hills Water System’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 Texas certifies.

The 3 labs Texas certifies closest to the area Stony Hills Water System serves, in a straight line. Call first: certification is test by test, and not every lab takes samples from homeowners.

Pace Analytical Services, LLC -Dallas TX
Fort Worth, TX · about 28 miles
Certified for bacteria
(817) 616-5030
Tarrant County Public Health Laboratory
Fort Worth, TX · about 32 miles
Certified for bacteria
(817) 321-4758
Eurofins Xenco, LLC -Dallas
Dallas, TX · about 34 miles
Certified for bacteria
(281) 240-4200

Texas Well Owner Network, Texas A&M AgriLife Extension: Well Informed screening events, where well owners bring in water samples to be screened for common contaminants, followed by an hour-long session explaining the results. Upcoming events are on the network's calendar. Trainings, Texas Well Owner Network.

All 80 certified labs for Texas