ZIP Code 78520
High RiskPFAS above EPA limits detected
3 compounds exceed EPA Maximum Contaminant Levels in water serving this ZIP code. Standard pitcher filters like Brita do not remove PFAS. See filter recommendations below.
14
PFAS Detected
3
Above EPA Limits
2
Water Systems
230%
Highest % of MCL
Compounds Exceeding EPA Limits
PFOS Exceeds EPA limit
0 ppt MCL: 4 ppt 230% of limit
Detected: 9.20 ppt
PFOA Exceeds EPA limit
0 ppt MCL: 4 ppt 118% of limit
Detected: 4.70 ppt
BROWNSVILLE PUBLIC UTILITIES BOARD
TX0310001 High RiskWater Type
Surface Water
PFAS Detected
8
Above MCL
2
State
Texas
Data Period
2023–2025
PFAS Test Results
| Compound | Detected | vs. EPA Limit | EPA Limit | Status |
|---|---|---|---|---|
PFOS Perfluorooctane sulfonic acid | 9.20ppt | 230% of limit
| 4 ppt | ⚠ Exceeds MCL |
PFOA Perfluorooctanoic acid | 4.70ppt | 118% of limit
| 4 ppt | ⚠ Exceeds MCL |
PFHxS Perfluorohexane sulfonic acid | 4.40ppt | 44% of limit
| 10 ppt | Below limit |
lithium | 51100.00ppt | No federal limit | — | Unregulated |
PFBA Perfluorobutanoic acid | 9.30ppt | No federal limit | — | Unregulated |
PFHxA Perfluorohexanoic acid | 8.00ppt | No federal limit | — | Unregulated |
PFPeA Perfluoropentanoic acid | 7.60ppt | No federal limit | — | Unregulated |
PFHpA Perfluoroheptanoic acid | 4.10ppt | No federal limit | — | Unregulated |
OLMITO WSC
TX0310026 High RiskWater Type
Surface Water
PFAS Detected
6
Above MCL
1
State
Texas
Data Period
2023–2025
PFAS Test Results
| Compound | Detected | vs. EPA Limit | EPA Limit | Status |
|---|---|---|---|---|
PFOS Perfluorooctane sulfonic acid | 4.50ppt | 113% of limit
| 4 ppt | ⚠ Exceeds MCL |
PFHxS Perfluorohexane sulfonic acid | 3.60ppt | 36% of limit
| 10 ppt | Below limit |
lithium | 77000.00ppt | No federal limit | — | Unregulated |
PFBA Perfluorobutanoic acid | 10.60ppt | No federal limit | — | Unregulated |
PFPeA Perfluoropentanoic acid | 5.30ppt | No federal limit | — | Unregulated |
PFHxA Perfluorohexanoic acid | 4.90ppt | No federal limit | — | Unregulated |
Note: ZIP code 78520 is served by 2 separate water utilities.
Results above show data for each system independently.
Data source: EPA Unregulated Contaminant Monitoring Rule, 5th cycle (UCMR 5) — January 2026 release.
UCMR 5 tested ~10,000 public water systems serving more than 25 people between 2023-2025 for 29 PFAS compounds.
Detection values represent the highest single-sample result measured at entry points to the distribution system.