Compliance record
Formal violations the EPA has on file for this supplier. A health-based violation means a contaminant limit or a required treatment was breached; the rest are monitoring or reporting failures — still violations, but not a measured health risk.
0
health-based violations
1
violations on file
0
still open
| Violation | Type | Status | Period |
|---|---|---|---|
| Other | Monitoring | Archived | 1988-09-01 → 1988-09-30 |
PFAS detected
PFAS are industrial “forever chemicals”. These are the EPA's latest
nationwide test results (2023–2025).
Other contaminants detected
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 this
system's samples — over 100% is worth reading, but is not by itself a
violation. Where a single sample came in higher than that percentile, it
is noted under the bar. Formal violations are listed separately.
| Contaminant | Level vs EPA limit | Detection rate | Source | Period |
|---|---|---|---|---|
| 1,1-Dichloroethylene | 14 µg/L 200% of the EPA limit, at the 95th percentile of samples — 7 µg/L
worst single sample: 36 µg/L | 1042/2473 | SYR4 | 2012–2019 |
| 1,2-Dichloroethane | 1.8 µg/L 36% of the EPA limit 5 µg/L
worst single sample: 2.3 µg/L | 613/1849 | SYR4 | 2012–2019 |
| Trichloroethylene | 40.6 µg/L 812% of the EPA limit, at the 95th percentile of samples — 5 µg/L
worst single sample: 64 µg/L | 429/2444 | SYR4 | 2012–2019 |
| Tetrachloroethylene | 55.55 µg/L 1111% of the EPA limit, at the 95th percentile of samples — 5 µg/L
worst single sample: 88 µg/L | 350/2445 | SYR4 | 2012–2019 |
| Nitrate | 8175 µg/L 82% of the EPA limit 10000 µg/L
worst single sample: 8814 µg/L | 306/312 | SYR4 | 2012–2019 |
| cis-1,2-Dichloroethylene | 6.4 µg/L 9.1% of the EPA limit 70 µg/L
worst single sample: 8.9 µg/L | 240/589 | SYR4 | 2012–2019 |
| TTHM | 54.8 µg/L 69% of the EPA limit 80 µg/L
worst single sample: 70 µg/L | 115/149 | SYR4 | 2012–2019 |
| Dibromoacetic Acid | 5.645 µg/L No EPA limit set
worst single sample: 6.5 µg/L | 112/124 | SYR4 | 2012–2019 |
| Total Haloacetic Acids (HAA5) | 24.9 µg/L 42% of the EPA limit 60 µg/L
worst single sample: 30 µg/L | 112/124 | SYR4 | 2012–2019 |
| Bromoform | 14 µg/L No EPA limit set
worst single sample: 24 µg/L | 111/148 | SYR4 | 2012–2019 |
| Bromodichloromethane | 15.6 µg/L No EPA limit set
worst single sample: 22 µg/L | 109/148 | SYR4 | 2012–2019 |
| Dibromochloromethane | 18 µg/L No EPA limit set
worst single sample: 24 µg/L | 109/148 | SYR4 | 2012–2019 |
| Chloroform | 14.95 µg/L No EPA limit set
worst single sample: 37 µg/L | 102/148 | SYR4 | 2012–2019 |
| Dichloroacetic Acid | 11.35 µg/L No EPA limit set
worst single sample: 15 µg/L | 94/124 | SYR4 | 2012–2019 |
| Trichloroacetic Acid | 7.4 µg/L No EPA limit set
worst single sample: 8.7 µg/L | 70/124 | SYR4 | 2012–2019 |
| Fluoride | 465 µg/L 12% of the EPA limit 4000 µg/L
worst single sample: 590 µg/L | 51/51 | SYR4 | 2012–2019 |
| Lead | 0.0 mg/L 0% of the EPA limit 0.0150 mg/L | 34/34 | LCR | 2025 |
| Monobromoacetic Acid | 2.2 µg/L No EPA limit set
worst single sample: 2.4 µg/L | 26/124 | SYR4 | 2012–2019 |
| Monochloroacetic Acid | 5.15 µg/L No EPA limit set
worst single sample: 6.2 µg/L | 26/124 | SYR4 | 2012–2019 |
| 1,2-Dichloropropane | 0.8040 µg/L 16% of the EPA limit 5 µg/L
worst single sample: 0.8300 µg/L | 14/206 | SYR4 | 2012–2019 |
| Selenium | 12 µg/L 24% of the EPA limit 50 µg/L
worst single sample: 15 µg/L | 13/21 | SYR4 | 2012–2018 |
| Arsenic | 4.2 µg/L 42% of the EPA limit 10 µg/L
worst single sample: 4.5 µg/L | 11/23 | SYR4 | 2012–2018 |
| Barium | 156.5 µg/L 7.8% of the EPA limit 2000 µg/L
worst single sample: 170 µg/L | 10/21 | SYR4 | 2012–2018 |
| Combined Uranium | 9.983 µg/L 33% of the EPA limit 30 µg/L | 9/13 | SYR4 | 2013–2019 |
| Nitrate-Nitrite | 8150 µg/L 82% of the EPA limit 10000 µg/L
worst single sample: 8300 µg/L | 6/8 | SYR4 | 2015–2018 |
| Copper | 8.02 µg/L 0.6% of the EPA limit 1300 µg/L
worst single sample: 9 µg/L | 5/21 | SYR4 | 2012–2018 |
| Lithium | 58 µg/L No EPA limit set | 4/14 | UCMR-5 | 2025 |
| Chromium | 6.27 µg/L 6.3% of the EPA limit 100 µg/L
worst single sample: 6.5 µg/L | 3/21 | SYR4 | 2012–2018 |
| Mercury | 0.2100 µg/L 11% of the EPA limit 2 µg/L | 1/21 | SYR4 | 2012–2018 |
74 contaminants tested, none detected
1,1,1-Trichloroethane1,1,2-Trichloroethane1,2,4-Trichlorobenzene1,2-DIBROMO-3-CHLOROPROPANE11Cl-PF3OUdS2,3,7,8-TCDD2,4,5-TP2,4-D4:2 Fts6:2 Fts8:2 Fts9Cl-PF3ONSAdonaAntimony, TotalBhc-GammaBenzeneBeryllium, TotalChlorobenzeneCyanideCadmiumCarbofuranCarbon TetrachlorideChlordaneCombined Radium (-226 And -228)DichloromethaneDalaponDi(2-ethylhexyl) PhthalateDinosebDiquatEthylene DibromideEndothallEndrinEthylbenzeneGlyphosateGross Beta Particle ActivityHfpo-DaHeptachlorHeptachlor EpoxideLassoLeadMethoxychlorNetfosaaNfdhaNmefosaaNitriteOxamylPFBSPfdaPfdoaPfeesaPfhpaPfhpsPFHXSPfmbaPfmpaPFNAPFOAPFOSPfpesPftaPftrdaPfunaPentachlorophenolPicloramStyreneThallium, TotalTolueneTotal Polychlorinated Biphenyls (PCB)ToxapheneVinyl ChlorideXylenes, TotalO-DichlorobenzeneP-Dichlorobenzenetrans-1,2-Dichloroethylene
Utility contact
Frequently asked questions about Gswc - Norwalk
Is Gswc - Norwalk tap water safe to drink?
EPA monitoring detected 32 contaminants in Gswc - Norwalk's water. A detection isn't the same as a violation — most levels are within federal limits. See each level and source above, and the utility's annual Consumer Confidence Report for its official compliance status.
What contaminants were detected in Gswc - Norwalk's water?
EPA monitoring detected 1,1-Dichloroethylene, 1,2-Dichloroethane, Trichloroethylene, Tetrachloroethylene, Nitrate, and others. The full list with the level and data source for each is above.
How many people does Gswc - Norwalk serve?
Gswc - Norwalk reports serving 43,167 people in California, per its EPA record.
Has Gswc - Norwalk had any water quality violations?
The EPA has 1 violation on file for Gswc - Norwalk, of which 0 are health-based (a contaminant limit or required treatment was breached) and 0 remain open. The rest are monitoring or reporting failures.
Where does this data come from?
Every figure is official EPA drinking-water monitoring — the Lead & Copper Rule, the UCMR-5 nationwide testing program, and the EPA Six-Year Review — not our own testing. Each number is labelled with its source and period.