What was found in ZIP 91978
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-Nitrite | 483000 µg/L 4830% of the EPA limit, at the 95th percentile of samples — 10000 µg/L Main supplier: HELIX WATER DISTRICT · 277,668 people · 2019 | 1/2 | SYR4 |
| Fluoride | 790 µg/L 20% of the EPA limit 4000 µg/L Main supplier: HELIX WATER DISTRICT · 277,668 people · 2019 | 1/2 | SYR4 |
| Nitrate | 499.58 µg/L 5% of the EPA limit 10000 µg/L Main supplier: HELIX WATER DISTRICT · 277,668 people · 2019 | 1/2 | SYR4 |
| Barium | 120 µg/L 6% of the EPA limit 2000 µg/L Main supplier: HELIX WATER DISTRICT · 277,668 people · 2019 | 1/2 | SYR4 |
| TTHM | 48 µg/L 60% of the EPA limit 80 µg/L Main supplier: HELIX WATER DISTRICT · 277,668 people · 2019
Highest in the ZIP: 55.1 µg/L — OTAY WATER DISTRICT · 238,008 people · 2019 | 2/2 | SYR4 |
| Lithium | 26 µg/L No EPA limit set Main supplier: HELIX WATER DISTRICT · 277,668 people · 2024
Highest in the ZIP: 28.9 µg/L — OTAY WATER DISTRICT · 238,008 people · 2024 | 2/2 | UCMR-5 |
| Dibromochloromethane | 19.95 µg/L No EPA limit set Main supplier: HELIX WATER DISTRICT · 277,668 people · 2019 | 2/2 | SYR4 |
| Bromodichloromethane | 14 µg/L No EPA limit set Main supplier: HELIX WATER DISTRICT · 277,668 people · 2019
Highest in the ZIP: 16 µg/L — OTAY WATER DISTRICT · 238,008 people · 2019 | 2/2 | SYR4 |
| Total Haloacetic Acids (HAA5) | 14 µg/L 23% of the EPA limit 60 µg/L Main supplier: HELIX WATER DISTRICT · 277,668 people · 2019
Highest in the ZIP: 16 µg/L — OTAY WATER DISTRICT · 238,008 people · 2019 | 2/2 | SYR4 |
| Chloroform | 11 µg/L No EPA limit set Main supplier: HELIX WATER DISTRICT · 277,668 people · 2019
Highest in the ZIP: 15.5 µg/L — OTAY WATER DISTRICT · 238,008 people · 2019 | 2/2 | SYR4 |
| Bromoform | 12 µg/L No EPA limit set Main supplier: HELIX WATER DISTRICT · 277,668 people · 2019 | 2/2 | SYR4 |
| Combined Uranium | 10.4196 µg/L 35% of the EPA limit 30 µg/L Main supplier: HELIX WATER DISTRICT · 277,668 people · 2018 | 1/2 | SYR4 |
| Dichloroacetic Acid | 7.4 µg/L No EPA limit set Main supplier: HELIX WATER DISTRICT · 277,668 people · 2019
Highest in the ZIP: 8.915 µg/L — OTAY WATER DISTRICT · 238,008 people · 2019 | 2/2 | SYR4 |
| Bromate | 8.87 µg/L 89% of the EPA limit 10 µg/L Main supplier: HELIX WATER DISTRICT · 277,668 people · 2019 | 1/2 | SYR4 |
| Monochloroacetic Acid | 4.95 µg/L No EPA limit set Highest in the ZIP: OTAY WATER DISTRICT · 238,008 people · 2019 | 1/2 | SYR4 |
| Dibromoacetic Acid | 3.9 µg/L No EPA limit set Main supplier: HELIX WATER DISTRICT · 277,668 people · 2019
Highest in the ZIP: 4.6 µg/L — OTAY WATER DISTRICT · 238,008 people · 2019 | 2/2 | SYR4 |
| Trichloroacetic Acid | 3.7 µg/L No EPA limit set Main supplier: HELIX WATER DISTRICT · 277,668 people · 2019
Highest in the ZIP: 4.3 µg/L — OTAY WATER DISTRICT · 238,008 people · 2019 | 2/2 | SYR4 |
| Arsenic | 3.125 µg/L 31% of the EPA limit 10 µg/L Main supplier: HELIX WATER DISTRICT · 277,668 people · 2019 | 1/2 | SYR4 |
| Mercury | 1.885 µg/L 94% of the EPA limit 2 µg/L Main supplier: HELIX WATER DISTRICT · 277,668 people · 2019 | 1/2 | SYR4 |
| Monobromoacetic Acid | 1.48 µg/L No EPA limit set Main supplier: HELIX WATER DISTRICT · 277,668 people · 2019 | 2/2 | SYR4 |
| Lead | 0.0 mg/L 0% of the EPA limit 0.0150 mg/L Main supplier: HELIX WATER DISTRICT · 277,668 people · 2024 | 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 91978
| Supplier | State | Population served |
|---|---|---|
| HELIX WATER DISTRICT | CA | 277,668 |
| OTAY WATER DISTRICT | CA | 238,008 |
Frequently asked questions about ZIP 91978 tap water
Is the tap water in ZIP 91978 safe to drink?
EPA testing detected 21 contaminants across the water suppliers serving ZIP 91978. 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 91978?
2 public water suppliers report EPA drinking-water monitoring for ZIP 91978. Each is listed above with its population served.
What contaminants are in ZIP 91978's water?
EPA monitoring detected Nitrate-Nitrite, Fluoride, Nitrate, Barium, TTHM, and others across this ZIP's suppliers. The full list with levels and sources is above.