ZIP Code 91761
High RiskPFAS above EPA limits detected
2 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
2
Above EPA Limits
2
Water Systems
750%
Highest % of MCL
Compounds Exceeding EPA Limits
PFOA Exceeds EPA limit
0 ppt MCL: 4 ppt 750% of limit
Detected: 30.00 ppt
PFOS Exceeds EPA limit
0 ppt MCL: 4 ppt 130% of limit
Detected: 5.20 ppt
WESTERN MWD
CA3310049 Low LevelWater Type
MX
PFAS Detected
3
Above MCL
0
State
California
Data Period
2023–2025
PFAS Test Results
| Compound | Detected | vs. EPA Limit | EPA Limit | Status |
|---|---|---|---|---|
PFHxS Perfluorohexane sulfonic acid | 3.40ppt | 34% of limit
| 10 ppt | Below limit |
PFPeA Perfluoropentanoic acid | 4.70ppt | No federal limit | — | Unregulated |
PFBS Perfluorobutane sulfonic acid | 3.00ppt | No federal limit | — | Unregulated |
ONTARIO MUNICIPAL UTILITIES COMPANY
CA3610034 High RiskWater Type
Groundwater
PFAS Detected
6
Above MCL
2
State
California
Data Period
2023–2025
PFAS Test Results
| Compound | Detected | vs. EPA Limit | EPA Limit | Status |
|---|---|---|---|---|
PFOA Perfluorooctanoic acid | 30.00ppt | 750% of limit
| 4 ppt | ⚠ Exceeds MCL |
PFOS Perfluorooctane sulfonic acid | 5.20ppt | 130% of limit
| 4 ppt | ⚠ Exceeds MCL |
PFHxS Perfluorohexane sulfonic acid | 4.20ppt | 42% of limit
| 10 ppt | Below limit |
PFHxA Perfluorohexanoic acid | 7.10ppt | No federal limit | — | Unregulated |
PFPeA Perfluoropentanoic acid | 6.70ppt | No federal limit | — | Unregulated |
PFBA Perfluorobutanoic acid | 6.40ppt | No federal limit | — | Unregulated |
Note: ZIP code 91761 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.