What was found in ZIP 91761
The level at this ZIP's main supplier, the highest level anywhere in it, the EPA limit for each, and where the figure comes from.
| Contaminant | Level vs EPA limit | Suppliers | Source |
|---|---|---|---|
| Nitrate | 12000 µg/L 120% of the EPA limit, at the 95th percentile of samples — 10000 µg/L Main supplier: ONTARIO MUNICIPAL UTILITIES COMPANY · 185,010 people · 2019 | 1/2 | SYR4 |
| Nitrate-Nitrite | 9840 µg/L 98% of the EPA limit 10000 µg/L Main supplier: ONTARIO MUNICIPAL UTILITIES COMPANY · 185,010 people · 2017 | 1/2 | SYR4 |
| Nitrite | 4525 µg/L 453% of the EPA limit, at the 95th percentile of samples — 1000 µg/L Main supplier: ONTARIO MUNICIPAL UTILITIES COMPANY · 185,010 people · 2019 | 1/2 | SYR4 |
| Fluoride | 400 µg/L 10% of the EPA limit 4000 µg/L Main supplier: ONTARIO MUNICIPAL UTILITIES COMPANY · 185,010 people · 2019 | 1/2 | SYR4 |
| Barium | 139.5 µg/L 7% of the EPA limit 2000 µg/L Main supplier: ONTARIO MUNICIPAL UTILITIES COMPANY · 185,010 people · 2019 | 1/2 | SYR4 |
| TTHM | 71.5 µg/L 89% of the EPA limit 80 µg/L Main supplier: ONTARIO MUNICIPAL UTILITIES COMPANY · 185,010 people · 2019 | 2/2 | SYR4 |
| Monochloroacetic Acid | 27 µg/L No EPA limit set Main supplier: ONTARIO MUNICIPAL UTILITIES COMPANY · 185,010 people · 2019
Highest in the ZIP: 32.7 µg/L — WESTERN MWD · 86,062 people · 2019 | 2/2 | SYR4 |
| Total Haloacetic Acids (HAA5) | 31.5 µg/L 53% of the EPA limit 60 µg/L Main supplier: ONTARIO MUNICIPAL UTILITIES COMPANY · 185,010 people · 2019 | 2/2 | SYR4 |
| Bromoform | 27.5 µg/L No EPA limit set Main supplier: ONTARIO MUNICIPAL UTILITIES COMPANY · 185,010 people · 2019 | 2/2 | SYR4 |
| Dibromochloromethane | 25 µg/L No EPA limit set Main supplier: ONTARIO MUNICIPAL UTILITIES COMPANY · 185,010 people · 2019 | 2/2 | SYR4 |
| Bromodichloromethane | 20.15 µg/L No EPA limit set Main supplier: ONTARIO MUNICIPAL UTILITIES COMPANY · 185,010 people · 2019 | 2/2 | SYR4 |
| Lithium | 16 µg/L No EPA limit set Highest in the ZIP: WESTERN MWD · 86,062 people · 2023 | 1/2 | UCMR-5 |
| Chloroform | 15 µg/L No EPA limit set Main supplier: ONTARIO MUNICIPAL UTILITIES COMPANY · 185,010 people · 2019 | 2/2 | SYR4 |
| Dibromoacetic Acid | 10.805 µg/L No EPA limit set Main supplier: ONTARIO MUNICIPAL UTILITIES COMPANY · 185,010 people · 2019 | 2/2 | SYR4 |
| Chromium | 7.45 µg/L 7.5% of the EPA limit 100 µg/L Main supplier: ONTARIO MUNICIPAL UTILITIES COMPANY · 185,010 people · 2019 | 1/2 | SYR4 |
| Monobromoacetic Acid | 7.16 µg/L No EPA limit set Main supplier: ONTARIO MUNICIPAL UTILITIES COMPANY · 185,010 people · 2019 | 2/2 | SYR4 |
| Dichloroacetic Acid | 5.405 µg/L No EPA limit set Main supplier: ONTARIO MUNICIPAL UTILITIES COMPANY · 185,010 people · 2019
Highest in the ZIP: 6.185 µg/L — WESTERN MWD · 86,062 people · 2019 | 2/2 | SYR4 |
| Trichloroacetic Acid | 4.205 µg/L No EPA limit set Main supplier: ONTARIO MUNICIPAL UTILITIES COMPANY · 185,010 people · 2019 | 2/2 | SYR4 |
| Arsenic | 2.39 µg/L 24% of the EPA limit 10 µg/L Main supplier: ONTARIO MUNICIPAL UTILITIES COMPANY · 185,010 people · 2019 | 1/2 | SYR4 |
| 1,2-DIBROMO-3-CHLOROPROPANE | 0.1200 µg/L 60% of the EPA limit 0.2000 µg/L Main supplier: ONTARIO MUNICIPAL UTILITIES COMPANY · 185,010 people · 2019 | 1/2 | SYR4 |
| PFOA | 0.0300 µg/L No EPA limit set Main supplier: ONTARIO MUNICIPAL UTILITIES COMPANY · 185,010 people · 2024 | 1/2 | UCMR-5 |
| Ethylene Dibromide | 0.0210 µg/L 42% of the EPA limit 0.0500 µg/L Main supplier: ONTARIO MUNICIPAL UTILITIES COMPANY · 185,010 people · 2019 | 1/2 | SYR4 |
| Pfhxa | 0.0071 µg/L No EPA limit set Main supplier: ONTARIO MUNICIPAL UTILITIES COMPANY · 185,010 people · 2024 | 1/2 | UCMR-5 |
| Pfpea | 0.0067 µg/L No EPA limit set Main supplier: ONTARIO MUNICIPAL UTILITIES COMPANY · 185,010 people · 2024 | 2/2 | UCMR-5 |
| Pfba | 0.0064 µg/L No EPA limit set Main supplier: ONTARIO MUNICIPAL UTILITIES COMPANY · 185,010 people · 2024 | 1/2 | UCMR-5 |
| PFOS | 0.0052 µg/L No EPA limit set Main supplier: ONTARIO MUNICIPAL UTILITIES COMPANY · 185,010 people · 2024 | 1/2 | UCMR-5 |
| PFHXS | 0.0042 µg/L No EPA limit set Main supplier: ONTARIO MUNICIPAL UTILITIES COMPANY · 185,010 people · 2024 | 2/2 | UCMR-5 |
| PFBS | 0.0030 µg/L No EPA limit set Highest in the ZIP: WESTERN MWD · 86,062 people · 2023 | 1/2 | UCMR-5 |
| Lead | 0.00060 mg/L 4% of the EPA limit 0.0150 mg/L Main supplier: ONTARIO MUNICIPAL UTILITIES COMPANY · 185,010 people · 2024
Highest in the ZIP: 0.0013 mg/L — WESTERN MWD · 86,062 people · 2025 | 2/2 | LCR |
Each bar shows the measured level as a share of the EPA limit: green is
well under, amber is close to it, red is over. For lead and copper the
limit applies to exactly the 90th-percentile figure shown, so red there
means a real exceedance. For everything else the limit applies to a
running annual average while the figure is the 95th percentile of the
system's samples — over 100% is worth reading, but is not by itself a
violation.
Formal violations are listed separately.
Water suppliers serving ZIP 91761
| Supplier | State | Population served |
|---|---|---|
| ONTARIO MUNICIPAL UTILITIES COMPANY | CA | 185,010 |
| WESTERN MWD | CA | 86,062 |
Frequently asked questions about ZIP 91761 tap water
Is the tap water in ZIP 91761 safe to drink?
EPA testing detected 29 contaminants across the water suppliers serving ZIP 91761. A detection isn't the same as a violation — most levels are within federal limits. See each level and source above, and your utility's annual Consumer Confidence Report for the official status.
Which water suppliers serve ZIP 91761?
2 public water suppliers report EPA drinking-water monitoring for ZIP 91761. Each is listed above with its population served.
What contaminants are in ZIP 91761's water?
EPA monitoring detected Nitrate, Nitrate-Nitrite, Nitrite, Fluoride, Barium, and others across this ZIP's suppliers. The full list with levels and sources is above.