Drinking water quality · 2024
· Verified
What's in Antioch, CA tap water
15 contaminants were measured in the Antioch, CA water system's 2024 annual report. Each is shown below against its federal limit — 2 sit at or above that limit.
- Reporting year
- 2024
- Contaminants measured
- 15
- Over federal limit
- 2
- Approaching the limit
- 1
- Worst contaminant
- Chromium, Hexavalent
- Service area
- CA
Where your water comes from · EPA SDWIS
Antioch, CA's drinking water comes from surface water, drawn from 2 sources.
Source
- ANTIOCH MUNICIPAL RESERVOIR
- SAN JOAQUIN RIVER INTAKE
Treatment
- ANTIOCH WTP
Distribution
Also buys water from CONTRA COSTA WATER DISTRICT, RANDALL-BOLD WATER TREATMENT PLANT, and 2 more.
Historical readings · EPA Six-Year Review (2012–2019)
1 contaminant historically over EPA limits in Antioch, CA
Every U.S. public water system reports compliance-monitoring data to EPA. The Six-Year Review releases the 2012–2019 window as a single dataset — here's what your system reported, year by year. Values shown are the highest detection per analyte per year, compared to the federal MCL.
| Contaminant | Worst detection | EPA limit | Years (2012–2019) |
|---|---|---|---|
BROMATE worst: 2014 | 0.01 mg/L 1.0× | 0.01 mg/L | '13'14'17 |
TTHM worst: 2018 | 0.074 mg/L 93% | 0.08 mg/L | '12'13'14'16'17'18'19 |
DICHLOROMETHANE worst: 2017 | 0.0034 mg/L within | 0.005 mg/L | '17 |
ARSENIC worst: 2013 | 0.0047 mg/L within below national p90 | 0.01 mg/L | '12'13'14'15'16'17'18'19 |
CADMIUM worst: 2017 | 0.0016 mg/L within near national p90 | 0.005 mg/L | '17 |
FLUORIDE worst: 2012 | 0.95 mg/L within | 4 mg/L | '12'13'14'15'16'17'18'19 |
HAA5 worst: 2017 | 0.0088 mg/L within | 0.06 mg/L | '12'13'14'16'17 |
NITRATE worst: 2013 | 0.994 mg/L within | 10 mg/L | '12'13'14'15'16'17'18'19 |
BARIUM worst: 2012 | 0.16 mg/L within near national p90 | 2 mg/L | '12'16'17'18'19 |
NITRATE NITRITE worst: 2017 | 0.72 mg/L within | 10 mg/L | '16'17'18'19 |
DEHP worst: 2019 | 0.00028 mg/L within | 0.006 mg/L | '19 |
CYANIDE worst: 2018 | 0.0011 mg/L within below national p90 | 0.2 mg/L | '18'19 |
DEHA worst: 2019 | 0.00021 mg/L within | 0.4 mg/L | '19 |
COPPER worst: 2019 | 0.32 mg/L below national p90 | — | '19 |
LEAD worst: 2019 | 0.0028 mg/L | — | '19 |
DBAA worst: 2012 | 0.0029 mg/L | — | '12'13'14'16'17 |
DCAA worst: 2012 | 0.0026 mg/L | — | '12'13'14'16'17 |
MBAA worst: 2016 | 0.0026 mg/L | — | '16 |
TCAA worst: 2017 | 0.0042 mg/L | — | '17 |
BROMODICHLOROMETHANE worst: 2012 | 0.0053 mg/L | — | '12'13'14'16'17'18'19 |
BROMOFORM worst: 2012 | 0.0076 mg/L | — | '12'13'14'16'17'18'19 |
CHLOROFORM worst: 2012 | 0.0029 mg/L | — | '12'13'14'16'17'18'19 |
DIBROMOCHLOROMETHANE worst: 2012 | 0.0079 mg/L | — | '12'13'14'16'17'18'19 |
Metals
| Contaminant | Measured | Federal limit | Status |
|---|---|---|---|
| Chromium, HexavalentHexavalent chromium ('chromium-6') — the more toxic form of chromium. | 0.11 ug/LAverageSystem-wide | 0.02 ug/LMCLG | At or above the limit |
| AluminumA common element sometimes used as a treatment coagulant. | 0.06 mg/LAverageSystem-wide | 0.6 mg/LMCLG | Within the limit |
| LithiumA naturally occurring element found in some groundwater. | 11.5 ug/LAverageSystem-wide | None set | Detected — no federal limit |
Disinfection byproducts
| Contaminant | Measured | Federal limit | Status |
|---|---|---|---|
| Chlorite | 0.2 mg/LRunning annual avgHighest Quarterly | 0.05 mg/LMCLG | At or above the limit |
Disinfectants
| Contaminant | Measured | Federal limit | Status |
|---|---|---|---|
| ChloramineA longer-lasting disinfectant made by combining chlorine with ammonia. | 2.6 mg/LRunning annual avgHighest Quarterly | 4 mg/LMCLG | Within the limit |
Microbial
| Contaminant | Measured | Federal limit | Status |
|---|---|---|---|
| Total ColiformA group of bacteria used as an indicator of overall water-system sanitation. | 0.5 %AverageSystem-wide | 5 %MCL | Within the limit |
Physical & aggregate
| Contaminant | Measured | Federal limit | Status |
|---|---|---|---|
| TurbidityA measure of cloudiness from suspended particles in the water. | 0.44 NTURangeSystem-wide | 95 NTUMCL | Within the limit |
Inorganic chemicals
| Contaminant | Measured | Federal limit | Status |
|---|---|---|---|
| Asbestos | Not detected MFLAverageSystem-wide | 7 MFLMCLG | Within the limit |
People also ask about Antioch, CA's water
+Is Antioch, CA tap water safe to drink in 2024?
The 2024 Consumer Confidence Report for the Antioch, CA water utility lists 2 contaminants at or above the federal limit: Chromium, Hexavalent and Chlorite. Whether that means the water is "unsafe" depends on which contaminant, how long the exposure, and individual health factors. The table on this page shows the measured value, the federal threshold, and the regulated statistic used for compliance.
+What contaminants are in Antioch, CA tap water?
15 contaminants were measured in Antioch, CA's 2024 Consumer Confidence Report, spanning metals, disinfection byproducts, and inorganic chemicals. 14 have an enforceable federal limit; the rest are detected but unregulated. Every measured value, in the utility's own units, is on this page.
+Which contaminants exceed federal limits in Antioch, CA tap water?
2 contaminants in Antioch, CA's 2024 report sit at or above the federal limit: Chromium, Hexavalent (5.5× the limit); Chlorite (4.0× the limit). The EPA enforces these limits against the regulated reporting statistic — typically a running annual average or 90th percentile — not a one-off sample spike.
+What is the worst contaminant in Antioch, CA tap water?
The contaminant with the highest measured value relative to its federal limit in the 2024 report is Chromium, Hexavalent, at 5.5× the federal threshold. It belongs to the metals family of contaminants.
+Are any contaminants in Antioch, CA tap water approaching the federal limit?
One contaminant is between 80% and 100% of the federal limit in this report: Fluoride. Approaching means measured but not in violation — a margin that can close quickly if conditions change.
+Where does the data on this page come from?
Every value is transcribed from Antioch, CA's 2024 Consumer Confidence Report — the annual drinking-water report every U.S. public water utility is required by federal law to publish. The original source document is archived and viewable on this site. A water-quality report covers an entire service area, not a single address.
+How often is Antioch, CA's water quality data updated?
Each U.S. public water utility publishes one Consumer Confidence Report per year, covering the prior calendar year's measurements. This page reflects the 2024 report; a new report will replace it once the utility publishes its next annual update.