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Updated 2026-10-15
County water report

Harris County Water Quality: 14 Cities Ranked by the Records

Harris County, Texas: 14 city reports built from EPA and utility records. A county has many suppliers; each city shows the system that serves it.

Find my systemOpen on the mapPrivate wells in Harris County
Across the county's systems

Highest result for each contaminant

One row per contaminant: the highest result any system in the county reported, against its limit. Open a row for the systems behind it.

LithiumDetected in 9 systems of 14 tested10 µg/L EPA health reference level (screening, not a legal limit) · US EPAHighest33.9 µg/L
Perfluorooctanesulfonic acid (PFOS)Detected in 7 systems of 14 tested4.0 ng/L federal MCL (2024) · US EPAHighest6.2 ng/L
  • CITY OF WEBSTER6.2 ng/LSample date: 2023-09-18 to 2024-08-06
  • CITY OF BAYTOWN6 ng/LSample date: 2023-04-19 to 2024-01-23
  • CITY OF PASADENA4.9 ng/LSample date: 2024-03-26 to 2026-01-22
  • CITY OF DEER PARK4.7 ng/LSample date: 2023-01-17 to 2023-10-13
  • CITY OF SOUTH HOUSTON4.2 ng/LSample date: 2024-02-28 to 2024-12-09
  • CITY OF GALENA PARK4.1 ng/LSample date: 2024-01-26 to 2024-10-18
  • HARRIS COUNTY WCID 364 ng/LSample date: 2024-04-23 to 2025-01-08
  • CITY OF BELLAIRENot detected · below 4.0 ng/L lab reporting limitSample date: 2024-11-15 to 2025-10-30
  • CITY OF HOUSTONNot detected · below 4.0 ng/L lab reporting limitSample date: 2023-02-06 to 2025-02-21
  • CITY OF HUMBLENot detected · below 4.0 ng/L lab reporting limitSample date: 2023-05-08 to 2024-04-26
  • CITY OF KATYNot detected · below 4.0 ng/L lab reporting limitSample date: 2024-04-12 to 2024-10-28
  • CITY OF LA PORTENot detected · below 4.0 ng/L lab reporting limitSample date: 2024-05-21 to 2025-03-12
  • CITY OF SEABROOKNot detected · below 4.0 ng/L lab reporting limitSample date: 2023-03-21 to 2023-12-15
  • CITY OF TOMBALLNot detected · below 4.0 ng/L lab reporting limitSample date: 2024-02-28 to 2024-08-29
Water hardnessDetected in 1 systemAesthetic, no federal health limit · USGSHighest7.9 gpg
Lead (90th percentile)Detected in 12 systems of 14 tested15 µg/L federal action level · US EPAHighest13.9 µg/L
Haloacetic acids (HAA5)Detected in 1 system60 ppb federal MCL · US EPAHighest40.8 ppb
Total trihalomethanes (TTHM)Detected in 1 system80 ppb federal MCL · US EPAHighest43.6 ppb
Perfluorohexanesulfonic acid (PFHxS)Detected in 7 systems of 14 tested10 ng/L federal MCL (2024) · US EPAHighest5.1 ng/L
  • CITY OF BAYTOWN5.1 ng/LSample date: 2023-04-19 to 2024-01-23
  • CITY OF GALENA PARK4.7 ng/LSample date: 2024-01-26 to 2024-10-18
  • CITY OF WEBSTER4.6 ng/LSample date: 2023-09-18 to 2024-08-06
  • CITY OF PASADENA4.3 ng/LSample date: 2024-03-26 to 2026-01-22
  • CITY OF SEABROOK3.7 ng/LSample date: 2023-03-21 to 2023-12-15
  • CITY OF DEER PARK3.6 ng/LSample date: 2023-01-17 to 2023-10-13
  • CITY OF SOUTH HOUSTON3.4 ng/LSample date: 2024-02-28 to 2024-12-09
  • CITY OF BELLAIRENot detected · below 3.0 ng/L lab reporting limitSample date: 2024-11-15 to 2025-10-30
  • CITY OF HOUSTONNot detected · below 3.0 ng/L lab reporting limitSample date: 2023-02-06 to 2025-02-21
  • CITY OF HUMBLENot detected · below 3.0 ng/L lab reporting limitSample date: 2023-05-08 to 2024-04-26
  • CITY OF KATYNot detected · below 3.0 ng/L lab reporting limitSample date: 2024-04-12 to 2024-10-28
  • CITY OF LA PORTENot detected · below 3.0 ng/L lab reporting limitSample date: 2024-05-21 to 2025-03-12
  • CITY OF TOMBALLNot detected · below 3.0 ng/L lab reporting limitSample date: 2024-02-28 to 2024-08-29
  • HARRIS COUNTY WCID 36Not detected · below 3.0 ng/L lab reporting limitSample date: 2024-04-23 to 2025-01-08
Perfluorobutanesulfonic acid (PFBS)Detected in 10 systems of 14 tested2,000 ng/L EPA health advisory (screening, not a legal limit) · US EPAHighest5.7 ng/L
5 more contaminants detectedShow
Perfluorohexanoic acid (PFHxA)Detected in 12 systems of 14 tested400,000 ng/L Michigan EGLE state MCL (strictest US state) · Michigan EGLEHighest9.8 ng/L
1H, 1H, 2H, 2H-perfluorooctane sulfonic acid (6:2 FTS)Detected in 2 systems of 14 testedNo federal or state limit; shown for transparencyHighest42.6 ng/L
  • CITY OF HOUSTON42.6 ng/LSample date: 2023-02-06 to 2025-02-21
  • CITY OF BELLAIRE9.5 ng/LSample date: 2024-11-15 to 2025-10-30
  • CITY OF BAYTOWNNot detected · below 5.0 ng/L lab reporting limitSample date: 2023-04-19 to 2024-01-23
  • CITY OF DEER PARKNot detected · below 5.0 ng/L lab reporting limitSample date: 2023-01-17 to 2023-10-13
  • CITY OF GALENA PARKNot detected · below 5.0 ng/L lab reporting limitSample date: 2024-01-26 to 2024-10-18
  • CITY OF HUMBLENot detected · below 5.0 ng/L lab reporting limitSample date: 2023-05-08 to 2024-04-26
  • CITY OF KATYNot detected · below 5.0 ng/L lab reporting limitSample date: 2024-04-12 to 2024-10-28
  • CITY OF LA PORTENot detected · below 5.0 ng/L lab reporting limitSample date: 2024-05-21 to 2025-03-12
  • CITY OF PASADENANot detected · below 5.0 ng/L lab reporting limitSample date: 2024-03-26 to 2026-01-22
  • CITY OF SEABROOKNot detected · below 5.0 ng/L lab reporting limitSample date: 2023-03-21 to 2023-12-15
  • CITY OF SOUTH HOUSTONNot detected · below 5.0 ng/L lab reporting limitSample date: 2024-02-28 to 2024-12-09
  • CITY OF TOMBALLNot detected · below 5.0 ng/L lab reporting limitSample date: 2024-02-28 to 2024-08-29
  • CITY OF WEBSTERNot detected · below 5.0 ng/L lab reporting limitSample date: 2023-09-18 to 2024-08-06
  • HARRIS COUNTY WCID 36Not detected · below 5.0 ng/L lab reporting limitSample date: 2024-04-23 to 2025-01-08
Perfluorobutanoic acid (PFBA)Detected in 12 systems of 14 testedNo federal or state limit; shown for transparencyHighest14.7 ng/L
Perfluoroheptanoic acid (PFHpA)Detected in 3 systems of 14 testedNo federal or state limit; shown for transparencyHighest3.7 ng/L
  • CITY OF BAYTOWN3.7 ng/LSample date: 2023-04-19 to 2024-01-23
  • CITY OF PASADENA3.3 ng/LSample date: 2024-03-26 to 2026-01-22
  • CITY OF WEBSTER3.2 ng/LSample date: 2023-09-18 to 2024-08-06
  • CITY OF BELLAIRENot detected · below 3.0 ng/L lab reporting limitSample date: 2024-11-15 to 2025-10-30
  • CITY OF DEER PARKNot detected · below 3.0 ng/L lab reporting limitSample date: 2023-01-17 to 2023-10-13
  • CITY OF GALENA PARKNot detected · below 3.0 ng/L lab reporting limitSample date: 2024-01-26 to 2024-10-18
  • CITY OF HOUSTONNot detected · below 3.0 ng/L lab reporting limitSample date: 2023-02-06 to 2025-02-21
  • CITY OF HUMBLENot detected · below 3.0 ng/L lab reporting limitSample date: 2023-05-08 to 2024-04-26
  • CITY OF KATYNot detected · below 3.0 ng/L lab reporting limitSample date: 2024-04-12 to 2024-10-28
  • CITY OF LA PORTENot detected · below 3.0 ng/L lab reporting limitSample date: 2024-05-21 to 2025-03-12
  • CITY OF SEABROOKNot detected · below 3.0 ng/L lab reporting limitSample date: 2023-03-21 to 2023-12-15
  • CITY OF SOUTH HOUSTONNot detected · below 3.0 ng/L lab reporting limitSample date: 2024-02-28 to 2024-12-09
  • CITY OF TOMBALLNot detected · below 3.0 ng/L lab reporting limitSample date: 2024-02-28 to 2024-08-29
  • HARRIS COUNTY WCID 36Not detected · below 3.0 ng/L lab reporting limitSample date: 2024-04-23 to 2025-01-08
Perfluoropentanoic acid (PFPeA)Detected in 12 systems of 14 testedNo federal or state limit; shown for transparencyHighest10.2 ng/L
21 PFAS tested, none detected in any systemShow

Tested in these 14 systems: CITY OF BAYTOWN, CITY OF BELLAIRE, CITY OF DEER PARK, CITY OF GALENA PARK, CITY OF HOUSTON, CITY OF HUMBLE, CITY OF KATY, CITY OF LA PORTE, CITY OF PASADENA, CITY OF SEABROOK, CITY OF SOUTH HOUSTON, CITY OF TOMBALL, CITY OF WEBSTER, HARRIS COUNTY WCID 36

  • 11-Chloroeicosafluoro-3-oxaundecane-1-sulfonic acid (11Cl-PF3OUdS)
  • 1H, 1H, 2H, 2H-perfluorodecane sulfonic acid (8:2 FTS)
  • 1H, 1H, 2H, 2H-perfluorohexane sulfonic acid (4:2 FTS)
  • 4,8-Dioxa-3H-perfluorononanoic acid (ADONA)
  • 9-Chlorohexadecafluoro-3-oxanone-1-sulfonic acid (9Cl-PF3ONS)
  • Hexafluoropropylene oxide dimer acid (HFPO-DA) (GenX chemicals)
  • N-ethyl perfluorooctanesulfonamidoacetic acid (NEtFOSAA)
  • N-methyl perfluorooctanesulfonamidoacetic acid (NMeFOSAA)
  • Nonafluoro-3,6-dioxaheptanoic acid (NFDHA)
  • Perfluoro (2-ethoxyethane) sulfonic acid (PFEESA)
  • Perfluoro-3-methoxypropanoic acid (PFMPA)
  • Perfluoro-4-methoxybutanoic acid (PFMBA)
  • Perfluorodecanoic acid (PFDA)
  • Perfluorododecanoic acid (PFDoA)
  • Perfluoroheptanesulfonic acid (PFHpS)
  • Perfluorononanoic acid (PFNA)
  • Perfluorooctanoic acid (PFOA)
  • Perfluoropentanesulfonic acid (PFPeS)
  • Perfluorotetradecanoic acid (PFTA)
  • Perfluorotridecanoic acid (PFTrDA)
  • Perfluoroundecanoic acid (PFUnA)
14 cities

Cities ranked by the records

Showing 6 of 14 cities · scores are system-level, not tap tests

Ranked by the Purity Score of each city's main water system, highest first. Scores belong to water systems; there is no county score. The score is computed only from contaminants measured in the published EPA record, so this ranks the record, not which city's water is safest. How the score works.

PFAS in Harris County6 of 14 city reports had a PFAS sample above a 2024 EPA limit
  1. Webster6.2 ng/L
  2. Baytown6 ng/L
  3. Pasadena4.9 ng/L
  4. Deer Park4.7 ng/L
  5. South Houston4.2 ng/L
  6. Galena Park4.1 ng/L
  7. Cloverleaf4 ng/L
4.0 ng/L federal MCL · PFOS, ng/LPFAS in Texas
Lead

0of 14 cities above the 15 µg/L action level

Based on each system's 90th-percentile result. Lead from household plumbing isn't in this record.

Lead in Texas
Hard water

1city reports hardness · Houston, 7.9 gpg

Hard on the USGS scale. An aesthetic measure with no federal health limit.

Hard water explained
Who supplies the county

Largest water systems

  1. HoustonCITY OF HOUSTON · TX1010013
    2,970,543 served
  2. PasadenaCITY OF PASADENA · TX1010293
    152,000 served
  3. BaytownCITY OF BAYTOWN · TX1010003
    86,004 served
  4. La PorteCITY OF LA PORTE · TX1010018
    36,569 served
  5. Deer ParkCITY OF DEER PARK · TX1010007
    34,495 served
  6. KatyCITY OF KATY · TX1010017
    25,253 served
  7. BellaireCITY OF BELLAIRE · TX1010004
    18,090 served
  8. TomballCITY OF TOMBALL · TX1010026
    17,532 served
  9. South HoustonCITY OF SOUTH HOUSTON · TX1010294
    17,397 served
  10. HumbleCITY OF HUMBLE · TX1010014
    15,616 served
Questions

Frequently asked

How does Harris County tap water compare across cities?

PurityMap ranks 14 cities in Harris County by the Purity Score of each city's main water system, computed only from contaminants measured in the published EPA record. Scores belong to water systems, not to cities. The highest published score is Bellaire's main water system: CITY OF BELLAIRE · PWSID TX1010004 · Purity Score 99 (Excellent) · Confidence: moderate · Assessed at the water-system level. The ranking compares the records, not which city's water is safest, and your own tap can differ with household plumbing.

How many Harris County cities had a PFAS sample above a 2024 EPA limit?

6 of 14 Harris County city reports had a PFAS sample above a 2024 EPA limit in EPA's UCMR 5 testing, including Webster (PFOS 6.2 ng/L), Baytown (PFOS 6 ng/L), Pasadena (PFOS 4.9 ng/L). That limit is judged on a yearly average, and water systems have until 2029 to meet it, so a single sample is not a violation. PFAS were detected at any level in 12.

Is there lead in Harris County tap water?

Utilities report lead as a 90th-percentile result from home taps. 12 of 14 Harris County cities reported a value above zero, and none was above the 15 µg/L federal action level. Lead usually comes from a building's own pipes and fixtures, so only a test at your tap tells you what you drink.

Does Harris County have hard water?

Hardness is published in utility water-quality reports for 1 Harris County city on record; the hardest is Houston at 7.9 grains per gallon. Hardness affects scale and appliances; it is not a health finding.

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