What was found in ZIP 90638
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 | 4746 µg/L 47% of the EPA limit 10000 µg/L Main supplier: SUBURBAN WATER SYSTEMS-WHITTIER · 66,045 people · 2019
Highest in the ZIP: 8175 µg/L — GSWC - NORWALK · 43,167 people · 2019 | 2/3 | SYR4 |
| Nitrate-Nitrite | 8150 µg/L 82% of the EPA limit 10000 µg/L Highest in the ZIP: GSWC - NORWALK · 43,167 people · 2018 | 1/3 | SYR4 |
| Fluoride | 310.5 µg/L 7.8% of the EPA limit 4000 µg/L Main supplier: SUBURBAN WATER SYSTEMS-WHITTIER · 66,045 people · 2018
Highest in the ZIP: 578 µg/L — SUBURBAN WATER SYSTEMS-LA MIRADA · 56,793 people · 2018 | 3/3 | SYR4 |
| Barium | 110 µg/L 5.5% of the EPA limit 2000 µg/L Main supplier: SUBURBAN WATER SYSTEMS-WHITTIER · 66,045 people · 2018
Highest in the ZIP: 156.49999999999997 µg/L — GSWC - NORWALK · 43,167 people · 2018 | 2/3 | SYR4 |
| TTHM | 19 µg/L 24% of the EPA limit 80 µg/L Main supplier: SUBURBAN WATER SYSTEMS-WHITTIER · 66,045 people · 2019
Highest in the ZIP: 67.85 µg/L — SUBURBAN WATER SYSTEMS-LA MIRADA · 56,793 people · 2019 | 3/3 | SYR4 |
| Lithium | 58 µg/L No EPA limit set Highest in the ZIP: GSWC - NORWALK · 43,167 people · 2025 | 2/3 | UCMR-5 |
| Tetrachloroethylene | 1.1099999999999999 µg/L 22% of the EPA limit 5 µg/L Main supplier: SUBURBAN WATER SYSTEMS-WHITTIER · 66,045 people · 2019
Highest in the ZIP: 55.55000000000001 µg/L — GSWC - NORWALK · 43,167 people · 2019 | 2/3 | SYR4 |
| Trichloroethylene | 0.7060 µg/L 14% of the EPA limit 5 µg/L Main supplier: SUBURBAN WATER SYSTEMS-WHITTIER · 66,045 people · 2019
Highest in the ZIP: 40.599999999999966 µg/L — GSWC - NORWALK · 43,167 people · 2019 | 2/3 | SYR4 |
| Chloroform | 1.5 µg/L No EPA limit set Main supplier: SUBURBAN WATER SYSTEMS-WHITTIER · 66,045 people · 2019
Highest in the ZIP: 26 µg/L — SUBURBAN WATER SYSTEMS-LA MIRADA · 56,793 people · 2019 | 3/3 | SYR4 |
| Total Haloacetic Acids (HAA5) | 3.1549999999999985 µg/L 5.3% of the EPA limit 60 µg/L Main supplier: SUBURBAN WATER SYSTEMS-WHITTIER · 66,045 people · 2019
Highest in the ZIP: 24.899999999999977 µg/L — GSWC - NORWALK · 43,167 people · 2019 | 3/3 | SYR4 |
| Bromodichloromethane | 3.6 µg/L No EPA limit set Main supplier: SUBURBAN WATER SYSTEMS-WHITTIER · 66,045 people · 2019
Highest in the ZIP: 20 µg/L — SUBURBAN WATER SYSTEMS-LA MIRADA · 56,793 people · 2019 | 3/3 | SYR4 |
| Dibromochloromethane | 7.859999999999999 µg/L No EPA limit set Main supplier: SUBURBAN WATER SYSTEMS-WHITTIER · 66,045 people · 2019
Highest in the ZIP: 18 µg/L — SUBURBAN WATER SYSTEMS-LA MIRADA · 56,793 people · 2019 | 3/3 | SYR4 |
| 1,1-Dichloroethylene | 14 µg/L 200% of the EPA limit, at the 95th percentile of samples — 7 µg/L Highest in the ZIP: GSWC - NORWALK · 43,167 people · 2019 | 1/3 | SYR4 |
| Bromoform | 6.85 µg/L No EPA limit set Main supplier: SUBURBAN WATER SYSTEMS-WHITTIER · 66,045 people · 2019
Highest in the ZIP: 14 µg/L — GSWC - NORWALK · 43,167 people · 2019 | 3/3 | SYR4 |
| Selenium | 11.999999999999993 µg/L 24% of the EPA limit 50 µg/L Highest in the ZIP: GSWC - NORWALK · 43,167 people · 2018 | 1/3 | SYR4 |
| Dichloroacetic Acid | 11.349999999999994 µg/L No EPA limit set Highest in the ZIP: GSWC - NORWALK · 43,167 people · 2019 | 2/3 | SYR4 |
| Combined Uranium | 3.2481999999999998 µg/L 11% of the EPA limit 30 µg/L Main supplier: SUBURBAN WATER SYSTEMS-WHITTIER · 66,045 people · 2019
Highest in the ZIP: 9.983 µg/L — GSWC - NORWALK · 43,167 people · 2019 | 3/3 | SYR4 |
| Trichloroacetic Acid | 8.1 µg/L No EPA limit set Highest in the ZIP: SUBURBAN WATER SYSTEMS-LA MIRADA · 56,793 people · 2019 | 2/3 | SYR4 |
| Copper | 8.02 µg/L 0.6% of the EPA limit 1300 µg/L Highest in the ZIP: GSWC - NORWALK · 43,167 people · 2018 | 1/3 | SYR4 |
| cis-1,2-Dichloroethylene | 1.3099999999999996 µg/L 1.9% of the EPA limit 70 µg/L Main supplier: SUBURBAN WATER SYSTEMS-WHITTIER · 66,045 people · 2019
Highest in the ZIP: 6.4 µg/L — GSWC - NORWALK · 43,167 people · 2019 | 2/3 | SYR4 |
| Chromium | 6.27 µg/L 6.3% of the EPA limit 100 µg/L Highest in the ZIP: GSWC - NORWALK · 43,167 people · 2018 | 1/3 | SYR4 |
| Dibromoacetic Acid | 3.1 µg/L No EPA limit set Main supplier: SUBURBAN WATER SYSTEMS-WHITTIER · 66,045 people · 2019
Highest in the ZIP: 5.644999999999999 µg/L — GSWC - NORWALK · 43,167 people · 2019 | 3/3 | SYR4 |
| Monochloroacetic Acid | 3.7 µg/L No EPA limit set Main supplier: SUBURBAN WATER SYSTEMS-WHITTIER · 66,045 people · 2019
Highest in the ZIP: 5.15 µg/L — GSWC - NORWALK · 43,167 people · 2019 | 2/3 | SYR4 |
| Arsenic | 2.3 µg/L 23% of the EPA limit 10 µg/L Main supplier: SUBURBAN WATER SYSTEMS-WHITTIER · 66,045 people · 2018
Highest in the ZIP: 4.74 µg/L — SUBURBAN WATER SYSTEMS-LA MIRADA · 56,793 people · 2018 | 3/3 | SYR4 |
| Di(2-ethylhexyl) Phthalate | 3.76 µg/L 63% of the EPA limit 6 µg/L Main supplier: SUBURBAN WATER SYSTEMS-WHITTIER · 66,045 people · 2019 | 1/3 | SYR4 |
| Monobromoacetic Acid | 1.5 µg/L No EPA limit set Main supplier: SUBURBAN WATER SYSTEMS-WHITTIER · 66,045 people · 2019
Highest in the ZIP: 2.2 µg/L — GSWC - NORWALK · 43,167 people · 2019 | 2/3 | SYR4 |
| 1,2-Dichloroethane | 1.8 µg/L 36% of the EPA limit 5 µg/L Highest in the ZIP: GSWC - NORWALK · 43,167 people · 2019 | 1/3 | SYR4 |
| 1,2-Dichloropropane | 0.8040 µg/L 16% of the EPA limit 5 µg/L Highest in the ZIP: GSWC - NORWALK · 43,167 people · 2019 | 1/3 | SYR4 |
| Mercury | 0.2100 µg/L 11% of the EPA limit 2 µg/L Highest in the ZIP: GSWC - NORWALK · 43,167 people · 2018 | 1/3 | SYR4 |
| PFOS | 0.0130 µg/L No EPA limit set Main supplier: SUBURBAN WATER SYSTEMS-WHITTIER · 66,045 people · 2024
Highest in the ZIP: 0.0160 µg/L — SUBURBAN WATER SYSTEMS-LA MIRADA · 56,793 people · 2025 | 2/3 | UCMR-5 |
| Pfpea | 0.0040 µg/L No EPA limit set Main supplier: SUBURBAN WATER SYSTEMS-WHITTIER · 66,045 people · 2024
Highest in the ZIP: 0.0150 µg/L — GSWC - NORWALK · 43,167 people · 2025 | 3/3 | UCMR-5 |
| Pfhxa | 0.0030 µg/L No EPA limit set Main supplier: SUBURBAN WATER SYSTEMS-WHITTIER · 66,045 people · 2024
Highest in the ZIP: 0.0130 µg/L — GSWC - NORWALK · 43,167 people · 2025 | 2/3 | UCMR-5 |
| Pfba | 0.0086 µg/L No EPA limit set Main supplier: SUBURBAN WATER SYSTEMS-WHITTIER · 66,045 people · 2024
Highest in the ZIP: 0.0095 µg/L — SUBURBAN WATER SYSTEMS-LA MIRADA · 56,793 people · 2025 | 3/3 | UCMR-5 |
| PFOA | 0.0063 µg/L No EPA limit set Main supplier: SUBURBAN WATER SYSTEMS-WHITTIER · 66,045 people · 2024
Highest in the ZIP: 0.0070 µg/L — SUBURBAN WATER SYSTEMS-LA MIRADA · 56,793 people · 2025 | 2/3 | UCMR-5 |
| PFBS | 0.0039 µg/L No EPA limit set Main supplier: SUBURBAN WATER SYSTEMS-WHITTIER · 66,045 people · 2024
Highest in the ZIP: 0.0042 µg/L — SUBURBAN WATER SYSTEMS-LA MIRADA · 56,793 people · 2025 | 2/3 | UCMR-5 |
| PFHXS | 0.0038 µg/L No EPA limit set Highest in the ZIP: SUBURBAN WATER SYSTEMS-LA MIRADA · 56,793 people · 2025 | 1/3 | UCMR-5 |
| Lead | 0.0 mg/L 0% of the EPA limit 0.0150 mg/L Main supplier: SUBURBAN WATER SYSTEMS-WHITTIER · 66,045 people · 2025 | 3/3 | 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 90638
| Supplier | State | Population served |
|---|---|---|
| SUBURBAN WATER SYSTEMS-WHITTIER | CA | 66,045 |
| SUBURBAN WATER SYSTEMS-LA MIRADA | CA | 56,793 |
| GSWC - NORWALK | CA | 43,167 |
Frequently asked questions about ZIP 90638 tap water
Is the tap water in ZIP 90638 safe to drink?
EPA testing detected 37 contaminants across the water suppliers serving ZIP 90638. 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 90638?
3 public water suppliers report EPA drinking-water monitoring for ZIP 90638. Each is listed above with its population served.
What contaminants are in ZIP 90638's water?
EPA monitoring detected Nitrate, Nitrate-Nitrite, Fluoride, Barium, TTHM, and others across this ZIP's suppliers. The full list with levels and sources is above.