Grand Oaks MUD

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: 2,013 people
Connections: 633
Water source: Groundwater bought from another system
Based in: Houston, TX
County: Montgomery
Owner: Local government

The ZIP code it serves

77355

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

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

Below EPA’s limits1

Total trihalomethanes (TTHM)

Forms or is added in treatment

Below EPA’s limits

2.7ppb

Highest yearly average, 2020 to 2026

2026, one sample: 1.2 ppb

Averaged by year, the highest was 2.7 ppb, in 2020, below EPA’s legal limit of 80 ppb. In 2026, the latest year on file, its one sample was 1.2 ppb. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 3.2 ppb, in 2019.

What handles it

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

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

Haloacetic acids (HAA5)
Lead
Nitrate

Violations since 2016

No health-based violations on file with EPA since 2016. There are 2 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 Texas’s own from 2020 on, with EPA’s national file for 2012 to 2019. Grand Oaks MUD’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 Aug. 18, 2020 to June 25, 2026.

Testing your own tap

Grand Oaks MUD’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 Grand Oaks MUD serves, in a straight line. Call first: certification is test by test, and not every lab takes samples from homeowners.

Water Utility Services, Inc.
Spring, TX · about 18 miles
Certified for bacteria
(281) 290-0704
Nova Biologicals, Inc.
Conroe, TX · about 21 miles
Certified for bacteria
(936) 756-5333
R&C Joy, Inc.
Katy, TX · about 22 miles
Certified for bacteria
(281) 858-5988

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