ZIP Code 91731
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.
9
PFAS Detected
3
Above EPA Limits
4
Water Systems
550%
Highest % of MCL
Compounds Exceeding EPA Limits
PFOS Exceeds EPA limit
0 ppt MCL: 4 ppt 110% of limit
Detected: 4.40 ppt
PFOA Exceeds EPA limit
0 ppt MCL: 4 ppt 138% of limit
Detected: 5.50 ppt
EL MONTE-CITY, WATER DEPT.
CA1910038 High RiskWater Type
Groundwater
PFAS Detected
2
Above MCL
1
State
California
Data Period
2023–2025
PFAS Test Results
| Compound | Detected | vs. EPA Limit | EPA Limit | Status |
|---|---|---|---|---|
PFOS Perfluorooctane sulfonic acid | 4.40ppt | 110% of limit
| 4 ppt | ⚠ Exceeds MCL |
PFHxS Perfluorohexane sulfonic acid | 3.20ppt | 32% of limit
| 10 ppt | Below limit |
SAN GABRIEL VALLEY WATER CO.-EL MONTE
CA1910039 Low LevelWater Type
Groundwater
PFAS Detected
2
Above MCL
0
State
California
Data Period
2023–2025
PFAS Test Results
| Compound | Detected | vs. EPA Limit | EPA Limit | Status |
|---|---|---|---|---|
PFBA Perfluorobutanoic acid | 10.00ppt | No federal limit | — | Unregulated |
PFPeA Perfluoropentanoic acid | 5.60ppt | No federal limit | — | Unregulated |
CAL/AM WATER COMPANY - SAN MARINO
CA1910139 Low LevelWater Type
Surface Water
PFAS Detected
2
Above MCL
0
State
California
Data Period
2023–2025
PFAS Test Results
| Compound | Detected | vs. EPA Limit | EPA Limit | Status |
|---|---|---|---|---|
lithium | 91900.00ppt | No federal limit | — | Unregulated |
PFBA Perfluorobutanoic acid | 5.30ppt | No federal limit | — | Unregulated |
GSWC-SOUTH ARCADIA
CA1910212 High RiskWater Type
Groundwater
PFAS Detected
3
Above MCL
2
State
California
Data Period
2023–2025
PFAS Test Results
| Compound | Detected | vs. EPA Limit | EPA Limit | Status |
|---|---|---|---|---|
PFOS Perfluorooctane sulfonic acid | 22.00ppt | 550% of limit
| 4 ppt | ⚠ Exceeds MCL |
PFOA Perfluorooctanoic acid | 5.50ppt | 138% of limit
| 4 ppt | ⚠ Exceeds MCL |
PFHxS Perfluorohexane sulfonic acid | 7.00ppt | 70% of limit
| 10 ppt | Below limit |
Note: ZIP code 91731 is served by 4 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.