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.
3
health-based violations
4
violations on file
0
still open
| Violation | Type | Status | Period |
|---|---|---|---|
| TT | Health-based | Resolved | 1999-02-01 → 1999-02-28 |
| TT | Health-based | Resolved | 1999-02-01 → 1999-02-28 |
| TT | Health-based | Resolved | 1999-02-01 → 1999-02-28 |
| Other | Monitoring | Archived | 1989-10-01 → 1989-10-31 |
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 |
|---|---|---|---|---|
| Fluoride | 800 µg/L 20% of the EPA limit 4000 µg/L
worst single sample: 900 µg/L | 192/325 | SYR4 | 2012–2019 |
| Nitrate | 1288.2 µg/L 13% of the EPA limit 10000 µg/L
worst single sample: 4859 µg/L | 130/720 | SYR4 | 2012–2019 |
| Arsenic | 5.845 µg/L 58% of the EPA limit 10 µg/L
worst single sample: 17 µg/L | 58/82 | SYR4 | 2012–2019 |
| Lead | 0.0031 mg/L 21% of the EPA limit 0.0150 mg/L | 54/54 | LCR | 2025 |
| Chloroform | 9.74 µg/L No EPA limit set
worst single sample: 13 µg/L | 50/50 | SYR4 | 2012–2019 |
| Dibromochloromethane | 14.1 µg/L No EPA limit set
worst single sample: 18 µg/L | 50/50 | SYR4 | 2012–2019 |
| TTHM | 39.3 µg/L 49% of the EPA limit 80 µg/L
worst single sample: 44 µg/L | 50/50 | SYR4 | 2012–2019 |
| Bromodichloromethane | 11.6 µg/L No EPA limit set
worst single sample: 14 µg/L | 49/50 | SYR4 | 2012–2019 |
| Total Haloacetic Acids (HAA5) | 10.7 µg/L 18% of the EPA limit 60 µg/L
worst single sample: 12 µg/L | 47/47 | SYR4 | 2012–2019 |
| Dichloroacetic Acid | 6.275 µg/L No EPA limit set
worst single sample: 7.9 µg/L | 42/47 | SYR4 | 2012–2019 |
| Bromoform | 9.37 µg/L No EPA limit set
worst single sample: 16 µg/L | 34/50 | SYR4 | 2012–2019 |
| Dibromoacetic Acid | 4.625 µg/L No EPA limit set
worst single sample: 5 µg/L | 28/47 | SYR4 | 2012–2019 |
| Gross Beta Particle Activity | 48.2 pCi/L No EPA limit set
worst single sample: 65 pCi/L | 15/33 | SYR4 | 2012–2019 |
| Bromate | 13.3 µg/L 133% of the EPA limit, at the 95th percentile of samples — 10 µg/L
worst single sample: 16 µg/L | 10/67 | SYR4 | 2012–2019 |
| Barium | 160 µg/L 8% of the EPA limit 2000 µg/L | 9/82 | SYR4 | 2012–2019 |
| Trichloroacetic Acid | 3.36 µg/L No EPA limit set
worst single sample: 4.2 µg/L | 8/47 | SYR4 | 2012–2019 |
| Combined Uranium | 1.39315 µg/L 4.6% of the EPA limit 30 µg/L | 7/44 | SYR4 | 2012–2019 |
| Dichloromethane | 2.98 µg/L 60% of the EPA limit 5 µg/L
worst single sample: 3.4 µg/L | 7/104 | SYR4 | 2012–2019 |
| Nitrate-Nitrite | 920 µg/L 9.2% of the EPA limit 10000 µg/L
worst single sample: 1100 µg/L | 5/25 | SYR4 | 2013–2019 |
| Copper | 278 µg/L 21% of the EPA limit 1300 µg/L
worst single sample: 320 µg/L | 4/84 | SYR4 | 2012–2019 |
| Cyanide | 1.57 µg/L 0.8% of the EPA limit 200 µg/L
worst single sample: 1.6 µg/L | 3/82 | SYR4 | 2012–2019 |
| Lead | 2.66 µg/L 18% of the EPA limit 15 µg/L
worst single sample: 2.8 µg/L | 3/80 | SYR4 | 2012–2019 |
| Asbestos | 0.2000 MFL 2.9% of the EPA limit 7 MFL | 2/71 | SYR4 | 2012–2019 |
| Cadmium | 1.595 µg/L 32% of the EPA limit 5 µg/L
worst single sample: 1.6 µg/L | 2/82 | SYR4 | 2012–2019 |
| Chromium | 29 µg/L 29% of the EPA limit 100 µg/L
worst single sample: 30 µg/L | 2/82 | SYR4 | 2012–2019 |
| Di(2-ethylhexyl) Phthalate | 0.3845 µg/L 6.4% of the EPA limit 6 µg/L
worst single sample: 0.3900 µg/L | 2/70 | SYR4 | 2012–2019 |
| Monobromoacetic Acid | 2.52 µg/L No EPA limit set
worst single sample: 2.6 µg/L | 2/47 | SYR4 | 2012–2019 |
| Nitrite | 494.004 µg/L 49% of the EPA limit 1000 µg/L
worst single sample: 520 µg/L | 2/338 | SYR4 | 2012–2019 |
| Selenium | 37.15 µg/L 74% of the EPA limit 50 µg/L
worst single sample: 38 µg/L | 2/82 | SYR4 | 2012–2019 |
| Di(2-ethylhexyl) Adipate | 0.2100 µg/L 0.1% of the EPA limit 400 µg/L | 1/70 | SYR4 | 2012–2019 |
83 contaminants tested, none detected
1,1,1-Trichloroethane1,1,2-Trichloroethane1,1-Dichloroethylene1,2,4-Trichlorobenzene1,2-DIBROMO-3-CHLOROPROPANE1,2-Dichloroethane1,2-Dichloropropane11Cl-PF3OUdS2,3,7,8-TCDD2,4,5-TP2,4-D4:2 Fts6:2 Fts8:2 Fts9Cl-PF3ONSAdonaAntimony, TotalAtrazineBhc-GammaBenzeneBenzo(A)PyreneBeryllium, TotalChlorobenzeneCarbofuranCarbon TetrachlorideChlordaneDalaponDinosebDiquatEthylene DibromideEndothallEndrinEthylbenzeneGlyphosateHexachlorobenzeneHfpo-DaHeptachlorHeptachlor EpoxideHexachlorocyclopentadieneLassoMercuryMethoxychlorMonochloroacetic AcidNetfosaaNfdhaNmefosaaOxamylPfbaPFBSPfdaPfdoaPfeesaPfhpaPfhpsPfhxaPFHXSPfmbaPfmpaPFNAPFOAPFOSPfpeaPfpesPftaPftrdaPfunaPentachlorophenolPicloramSimazineStyreneTetrachloroethyleneThallium, TotalTolueneTotal Polychlorinated Biphenyls (PCB)ToxapheneTrichloroethyleneVinyl ChlorideXylenes, Totalcis-1,2-DichloroethyleneLithiumO-DichlorobenzeneP-Dichlorobenzenetrans-1,2-Dichloroethylene
Utility contact
Frequently asked questions about Contra Costa Water District
Is Contra Costa Water District tap water safe to drink?
EPA monitoring detected 30 contaminants in Contra Costa Water District'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 Contra Costa Water District's water?
EPA monitoring detected Fluoride, Nitrate, Arsenic, Lead, Chloroform, and others. The full list with the level and data source for each is above.
How many people does Contra Costa Water District serve?
Contra Costa Water District reports serving 198,000 people in California, per its EPA record.
Has Contra Costa Water District had any water quality violations?
The EPA has 4 violations on file for Contra Costa Water District, of which 3 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.