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Harris County MUD 405

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
657 people
Connections
219
Water source
Groundwater
Based in
Houston, TX
County
Harris
Owner
Local government
The ZIP code it serves

77447

The short answer

1 result is above the health goal. The worst: Arsenic, above the health goal. No health-based violations on file since 2016.

What handles it

What was found

Arsenic, total trihalomethanes (TTHM), fluoride, haloacetic acids (HAA5), nitrate, chromium (total) and uranium: Texas’s own results, samples taken from Aug. 5, 2020 to Sept. 9, 2026, with EPA’s 2012 to 2019 file for earlier years.

Above the health goal1

Arsenic

Comes from the source

Above the health goal

6.7ppb

Highest yearly average, 2022 to 2025

2025, one sample: 4.4 ppb

Averaged by year, the highest was 6.7 ppb, in 2022: below EPA’s legal limit of 10 ppb, but above its health goal of zero. In 2025, the latest year on file, its one sample was 4.4 ppb. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 6.0 ppb, in 2019.

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

Below EPA’s limits

18.4ppb

Highest yearly average, 2020 to 2026

Averaged by year, the highest was 18.4 ppb, in 2026, below EPA’s legal limit of 80 ppb. Its highest single sample was 36.9 ppb. That was also the latest year on file.

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

0.31ppm

Highest yearly average, 2022 to 2025

2025: not found

Averaged by year, the highest was 0.31 ppm, in 2022, below EPA’s legal limit of 4.0 ppm. In 2025, 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 0.31 ppm, in 2016.

What handles it

Haloacetic acids (HAA5)

Forms or is added in treatment

Below EPA’s limits

4.5ppb

Highest yearly average, 2020 to 2026

2026 average: 0.7 ppb

Averaged by year, the highest was 4.5 ppb, in 2025, below EPA’s legal limit of 60 ppb. Its highest single sample was 9.0 ppb. In 2026, the latest year on file, its two samples averaged 0.7 ppb.

What handles it

No certification claim covers this compound yet.

Nitrate

Comes from the source

Below EPA’s limits

0.11ppm

Highest sample; found in 4 of 7

2026: not found

The highest sample, in 2020, was 0.11 ppm, below EPA’s legal limit of 10 ppm. 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 sample of 0.12 ppm, in 2018.

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.
  • Chromium (total)
  • Lead
  • Uranium

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

    Claim: Arsenic (Pentavalent)<=50 ppb Reduction

    For: Arsenic

    Other certifiers’ wording: Arsenic (III) (50 ppb influent level)

  • NSF/ANSI 58

    Claim: Arsenic (Pentavalent)<=50 ppb Reduction

    For: Arsenic

    Other certifiers’ wording: 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

Compare five-year costs

The best reverse osmosis systems, ranked

Violations since 2016

No health-based violations on file with EPA since 2016. There is 1 monitoring or reporting violation: a sample missed, late or not reported.

What this report can’t tell you

  • Everything else. Arsenic, total trihalomethanes (TTHM), fluoride, haloacetic acids (HAA5), nitrate, chromium (total) and uranium results here are Texas’s own from 2020 on, with EPA’s national file for 2012 to 2019. Harris County MUD 405’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. 5, 2020 to Sept. 9, 2026.

Testing your own tap

Harris County MUD 405’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 Harris County MUD 405 serves, in a straight line. Call first: certification is test by test, and not every lab takes samples from homeowners.

  • R&C Joy, Inc.

    Katy, TX · about 16 miles

    Certified for bacteria

    (281) 858-5988

  • Eurofins EMLab P&K – Houston

    Houston, TX · about 20 miles

    Certified for bacteria

    (281) 940-2580

  • Water Utility Services, Inc.

    Spring, TX · about 22 miles

    Certified for bacteria

    (281) 290-0704

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

Sources

PWSID TX1013362. Rebuilt from EPA data on Oct. 18, 2026.

Also in Harris County

All Texas utilities

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