City of Rio Vista

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: 1,040 people
Connections: 469
Water source: Groundwater
Based in: Rio Vista, TX
County: Johnson
Owner: Local government

The ZIP code it serves

76093

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. 1 health-based violation since 2016.

What was found

Total trihalomethanes (TTHM), fluoride, chromium (total), haloacetic acids (HAA5), nitrate, arsenic and uranium: Texas’s own results, samples taken from June 25, 2020 to June 18, 2026, with EPA’s 2012 to 2019 file for earlier years.

Below EPA’s limits5

Total trihalomethanes (TTHM)

Forms or is added in treatment

Below EPA’s limits

18.8ppb

Highest yearly average, 2020 to 2026

Averaged by year, the highest was 18.8 ppb, in 2026, 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 6.6 ppb, in 2019.

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

Below EPA’s limits

0.38ppm

Highest yearly average, 2020 to 2026

2026, one sample: 0.36 ppm

Averaged by year, the highest was 0.38 ppm, in 2024, below EPA’s legal limit of 4.0 ppm. Its highest single sample was 0.38 ppm. In 2026, the latest year on file, its one sample was 0.36 ppm. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 0.45 ppm, in 2012.

What handles it

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

Chromium (total)

Comes from the source

Below EPA’s limits

5.9ppb

Highest yearly average, 2020 to 2026

2026: not found

Averaged by year, the highest was 5.9 ppb, in 2021, below EPA’s legal limit of 100 ppb. In 2026, the latest year on file, it wasn’t found in its one sample. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 3.1 ppb, in 2014.

What handles it

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

Haloacetic acids (HAA5)

Forms or is added in treatment

Below EPA’s limits

2.3ppb

Highest yearly average, 2020 to 2026

2026: not found

Averaged by year, the highest was 2.3 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. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 8.9 ppb, in 2017.

What handles it

No certification claim covers this compound yet.

Nitrate

Comes from the source

Below EPA’s limits

0.056ppm

Highest sample; found in 14 of 15

2026 average: 0.054 ppm

The highest sample, in 2026, was 0.056 ppm, below EPA’s legal limit of 10 ppm. That was also the latest year on file, and its two samples averaged 0.054 ppm. Earlier, from 2012 to 2019, EPA’s file shows a highest sample of 0.065 ppm, in 2012.

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

Contaminant or rule	Type	Period	Measured	Status
Lead and Copper Rule Revisions	The required inventory of lead service lines was not completed or submitted on time.EPA: LSL Inventory	Oct. 17, 2024	—	Resolved
Health-based violations only. Resolved and archived mean the utility returned to compliance or the state closed the record. 28 monitoring or reporting violations not shown.

What this report can’t tell you

Everything else. Total trihalomethanes (TTHM), fluoride, chromium (total), haloacetic acids (HAA5), nitrate, arsenic and uranium results here are Texas’s own from 2020 on, with EPA’s national file for 2012 to 2019. City of Rio Vista’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 June 25, 2020 to June 18, 2026.

Testing your own tap

City of Rio Vista’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 City of Rio Vista serves, in a straight line. Call first: certification is test by test, and not every lab takes samples from homeowners.

Environmental Monitoring Lab
Hillsboro, TX · about 20 miles
Certified for bacteria
(254) 582-2622
Bio-Chem Lab, Inc.
West, TX · about 35 miles
Certified for bacteria, lead and copper
(254) 829-8001
Tarrant County Public Health Laboratory
Fort Worth, TX · about 36 miles
Certified for bacteria
(817) 321-4758

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