Drinking water quality · 2024
· Verified
What's in Contra Costa Water District, CA tap water
103 contaminants were measured in the Contra Costa Water District, CA water system's 2024 annual report. Each is shown below against its federal limit — 4 sit at or above that limit.
- Reporting year
- 2024
- Contaminants measured
- 103
- Over federal limit
- 4
- Approaching the limit
- 1
- Worst contaminant
- Chlorite
- Service area
- CA
4.0× the limit
state-level CCR
At or above the federal limit
Approaching the limit (≥ 80%)
Where your water comes from · EPA SDWIS
Contra Costa Water District, CA's drinking water comes from surface water, drawn from 10 sources.
Source
10surface water
- CANAL AT CLYDE
- MALLARD RESERVOIR
- MARTINEZ RESERVOIR
- CONTRA COSTA CANAL
- + 6 more
Treatment
1treatment plant
- BOLLMAN WATER TREATMENT PLANT
Distribution
0storage units
Also buys water from RANDALL-BOLD WATER TREATMENT PLANT, EAST BAY MUD.
Source: EPA SDWIS facilities inventory. Methodology.
Disinfection byproducts
| Contaminant | Measured | Federal limit | Status |
|---|---|---|---|
| Chlorite | 0.2 mg/LRunning annual avgHighest Quarterly | 0.05 mg/LMCLG | At or above the limit |
| PerchlorateA chemical used in rocket fuel and fireworks that can also form during disinfection. | 4.6 UG/LAverageDistribution | 6 UG/LMCL | Within the limit |
| TTHMTotal trihalomethanes — a group of four chemicals (including chloroform) formed when chlorine reacts with natural organic matter. | 28 UG/LAverageEntry point | 80 UG/LMCL | Within the limit |
| HAA5Haloacetic acids — a group of five disinfection byproducts formed when disinfectants react with organic matter. | 10.602916666666667 UG/LAverageDistribution | 60 UG/LMCL | Within the limit |
| BromateA disinfection byproduct formed when bromide-containing water is treated with ozone. | Not detected UG/LHighest single sampleEntry point | 10 UG/LMCL | None detected |
| BromodichloromethaneA trihalomethane disinfection byproduct. | 7.7 UG/LAverageEntry point | None set | Detected — no federal limit |
| BromoformA trihalomethane disinfection byproduct. | 7.2 UG/LAverageEntry point | None set | Detected — no federal limit |
| ChloroformA trihalomethane formed when chlorine reacts with organic matter in water. | 5.8 UG/LAverageDistribution | None set | Detected — no federal limit |
| DibromochloromethaneA trihalomethane disinfection byproduct. | 8.666666666666666 UG/LAverageEntry point | None set | Detected — no federal limit |
Physical & aggregate
| Contaminant | Measured | Federal limit | Status |
|---|---|---|---|
| OdorA measure of detectable smell in the water. | 5.8 TONAverageEntry point | 3 TONMCL | At or above the limit |
| TurbidityA measure of cloudiness from suspended particles in the water. | 6.36 NTUAverageSource water | 5 NTUMCL | At or above the limit |
| ColorA measure of visible tint in the water. | 14.4 UNITSAverageEntry point | 15 UNITSMCL | Approaching the limit |
| Specific ConductanceA measure of how well water conducts electricity, which tracks dissolved mineral content. | 828 UMHO/CMAverageDistribution | 1600 UMHO/CMMCL | Within the limit |
| Total Dissolved SolidsTotal dissolved solids — the combined content of all dissolved minerals and salts. | 448 MG/LAverageDistribution | 1000 MG/LMCL | Within the limit |
| AlkalinityA measure of the water's capacity to neutralize acids. | 48 MG/LAverageSource water | None set | Detected — no federal limit |
| HardnessA measure of dissolved calcium and magnesium minerals. | 76.64 MG/LAverageSource water | None set | Detected — no federal limit |
| pHA measure of how acidic or basic the water is. | 8.228 PHAverageEntry point | None set | Detected — no federal limit |
Metals
| Contaminant | Measured | Federal limit | Status |
|---|---|---|---|
| IronA naturally occurring metal common in groundwater. | 428 UG/LAverageSource water | 300 UG/LMCL | At or above the limit |
| ManganeseA naturally occurring metal from soil and rock. | 35.8 UG/LAverageSource water | 50 UG/LMCL | Within the limit |
| AluminumA common element sometimes used as a treatment coagulant. | 258.4 UG/LAverageSource water | 1000 UG/LMCL | Within the limit |
| ArsenicA naturally occurring element that also enters water from industry and agriculture. | 2.4 UG/LAverageSource water | 10 UG/LMCL | Within the limit |
| BariumA metal from erosion of natural deposits and industrial discharge. | 72 UG/LAverageSource water | 1000 UG/LMCL | Within the limit |
| Chromium, HexavalentHexavalent chromium ('chromium-6') — the more toxic form of chromium. | 0.1325 UG/LAverageSource water | 10 UG/LMCL | Within the limit |
| CopperA metal that enters water from corroding household plumbing. | 9.8 UG/LAverageEntry point | 1000 UG/LMCL | Within the limit |
| Antimony | Not detected UG/LHighest single sampleSource water | 6 UG/LMCL | None detected |
| Beryllium | Not detected UG/LHighest single sampleEntry point | 4 UG/LMCL | None detected |
| Cadmium | Not detected UG/LHighest single sampleSource water | 5 UG/LMCL | None detected |
| LeadA toxic metal that leaches into water from old service lines, solder, and plumbing fixtures. | Not detected UG/LHighest single sampleEntry point | None set | None detected |
| MercuryA toxic metal from erosion of natural deposits and industrial runoff. | Not detected UG/LHighest single sampleDistribution | 2 UG/LMCL | None detected |
| NickelA metal from natural deposits and industrial discharge. | Not detected UG/LHighest single sampleEntry point | 100 UG/LMCL | None detected |
| SeleniumA trace element from natural deposits and industrial discharge. | Not detected UG/LHighest single sampleEntry point | 50 UG/LMCL | None detected |
| Thallium | Not detected UG/LHighest single sampleEntry point | 2 UG/LMCL | None detected |
| ZincA naturally occurring metal that can also enter water from corroding pipes. | Not detected UG/LHighest single sampleDistribution | 5000 UG/LMCL | None detected |
| CalciumA naturally occurring mineral that contributes to water hardness. | 11 MG/LAverageDistribution | None set | Detected — no federal limit |
| LithiumA naturally occurring element found in some groundwater. | 11.5 ug/LAverageSystem-wide | None set | Detected — no federal limit |
| MagnesiumA naturally occurring mineral that contributes to water hardness. | 8.6 MG/LAverageSource water | None set | Detected — no federal limit |
| PotassiumA naturally occurring mineral from rock and soil. | 2 MG/LAverageDistribution | None set | Detected — no federal limit |
| SodiumA naturally occurring salt component. | 130 MG/LAverageDistribution | None set | Detected — no federal 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 |
Inorganic chemicals
| Contaminant | Measured | Federal limit | Status |
|---|---|---|---|
| ChlorideA naturally occurring salt compound. | 170 MG/LAverageDistribution | 500 MG/LMCL | Within the limit |
| FluorideA mineral often added to drinking water to help prevent tooth decay. | 0.62 MG/LAverageDistribution | 2 MG/LMCL | Within the limit |
| NitriteA compound from fertilizer runoff, sewage, and erosion of natural deposits. | 0.1975 MG/LAverageDistribution | 1 MG/LMCL | Within the limit |
| SulfateA naturally occurring mineral from rock and soil. | 52 MG/LAverageDistribution | 500 MG/LMCL | Within the limit |
| NitrateA compound from fertilizer runoff, septic systems, and erosion of natural deposits. | 0.8300000000000001 MG/LAverageDistribution | 10 MG/LMCL | Within the limit |
| Cyanide | 1 UG/LAverageDistribution | 150 UG/LMCL | Within the limit |
| Asbestos | Not detected MFLHighest single sampleEntry point | 7 MFLMCL | None detected |
| Ammonia | 0.13599999999999998 MG/LAverageEntry point | None set | Detected — no federal limit |
| BromideA naturally occurring salt found in source water. | 0.11600000000000002 MG/LAverageSource water | None set | Detected — no federal limit |
Other
| Contaminant | Measured | Federal limit | Status |
|---|---|---|---|
| Nitrate Nitrite | 1.01 MG/LAverageDistribution | 10 MG/LMCL | Within the limit |
| Carbofuran | Not detected UG/LHighest single sampleSource water | 18 UG/LMCL | None detected |
| Carbon Tetrachloride | Not detected UG/LHighest single sampleEntry point | 0.5 UG/LMCL | None detected |
| Chlordane | Not detected UG/LHighest single sampleEntry point | 0.1 UG/LMCL | None detected |
| Chlorobenzene | Not detected UG/LHighest single sampleSource water | 70 UG/LMCL | None detected |
| Chromium | Not detected UG/LHighest single sampleSource water | 50 UG/LMCL | None detected |
| Cis Dichloroethylene 12 | Not detected UG/LHighest single sampleSource water | 6 UG/LMCL | None detected |
| Deha | Not detected UG/LHighest single sampleEntry point | 400 UG/LMCL | None detected |
| Dehp | Not detected UG/LHighest single sampleEntry point | 4 UG/LMCL | None detected |
| Dichloroethane 12 | Not detected UG/LHighest single sampleEntry point | 0.5 UG/LMCL | None detected |
| Dichloroethylene 11 | Not detected UG/LHighest single sampleEntry point | 6 UG/LMCL | None detected |
| Dichloropropane 12 | Not detected UG/LHighest single sampleSource water | 5 UG/LMCL | None detected |
| Dinoseb | Not detected UG/LHighest single sampleEntry point | 7 UG/LMCL | None detected |
| Diquat | Not detected UG/LHighest single sampleEntry point | 20 UG/LMCL | None detected |
| Edb | Not detected UG/LHighest single sampleEntry point | 0.05 UG/LMCL | None detected |
| Endothall | Not detected UG/LHighest single sampleEntry point | 100 UG/LMCL | None detected |
| Endrin | Not detected UG/LHighest single sampleSource water | 2 UG/LMCL | None detected |
| Glyphosate | Not detected UG/LHighest single sampleSource water | 700 UG/LMCL | None detected |
| Heptachlor | Not detected UG/LHighest single sampleEntry point | 0.01 UG/LMCL | None detected |
| Heptachlor Epoxide | Not detected UG/LHighest single sampleSource water | 0.01 UG/LMCL | None detected |
| Hexachlorobenzene | Not detected UG/LHighest single sampleSource water | 1 UG/LMCL | None detected |
| Hexachlorocyclopentadiene | Not detected UG/LHighest single sampleEntry point | 50 UG/LMCL | None detected |
| Methoxychlor | Not detected UG/LHighest single sampleEntry point | 30 UG/LMCL | None detected |
| O Dichlorobenzene | Not detected UG/LHighest single sampleSource water | 600 UG/LMCL | None detected |
| Oxamyl | Not detected UG/LHighest single sampleSource water | 50 UG/LMCL | None detected |
| P Dichlorobenzene | Not detected UG/LHighest single sampleEntry point | 5 UG/LMCL | None detected |
| Pcb Total | Not detected UG/LHighest single sampleSource water | 0.5 UG/LMCL | None detected |
| Pce | Not detected UG/LHighest single sampleEntry point | 5 UG/LMCL | None detected |
| Pentachlorophenol | Not detected UG/LHighest single sampleSource water | 1 UG/LMCL | None detected |
| Picloram | Not detected UG/LHighest single sampleSource water | 500 UG/LMCL | None detected |
| Styrene | Not detected UG/LHighest single sampleSource water | 100 UG/LMCL | None detected |
| Tce | Not detected UG/LHighest single sampleSource water | 5 UG/LMCL | None detected |
| Toxaphene | Not detected UG/LHighest single sampleEntry point | 3 UG/LMCL | None detected |
| Trans Dichloroethylene 12 | Not detected UG/LHighest single sampleEntry point | 10 UG/LMCL | None detected |
| Trichlorobenzene 124 | Not detected UG/LHighest single sampleSource water | 5 UG/LMCL | None detected |
| Trichloroethane 111 | Not detected UG/LHighest single sampleEntry point | 200 UG/LMCL | None detected |
| Trichloroethane 112 | Not detected UG/LHighest single sampleSource water | 5 UG/LMCL | None detected |
| Twofourd | Not detected UG/LHighest single sampleSource water | 70 UG/LMCL | None detected |
| Vinyl Chloride | Not detected UG/LHighest single sampleSource water | 0.5 UG/LMCL | None detected |
| Dbaa | 3.513333333333333 UG/LAverageEntry point | None set | Detected — no federal limit |
| Dcaa | 6.16875 UG/LAverageDistribution | None set | Detected — no federal limit |
| Mbaa | 0.41 UG/LAverageEntry point | None set | Detected — no federal limit |
| Mcaa | 0.65 UG/LAverageEntry point | None set | Detected — no federal limit |
| Tcaa | 1.06 UG/LAverageDistribution | None set | Detected — no federal 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 |
VOCs & pesticides
| Contaminant | Measured | Federal limit | Status |
|---|---|---|---|
| 1,2,3-TCP | Not detected UG/LHighest single sampleEntry point | 0.005 UG/LMCL | None detected |
| AtrazineA widely used agricultural herbicide that reaches water through runoff. | Not detected UG/LHighest single sampleSource water | 1 UG/LMCL | None detected |
| Benzene | Not detected UG/LHighest single sampleEntry point | 1 UG/LMCL | None detected |
| Benzo(a)pyrene | Not detected UG/LHighest single sampleSource water | 0.2 UG/LMCL | None detected |
| Dalapon | Not detected UG/LHighest single sampleSource water | 200 UG/LMCL | None detected |
| Dichloromethane | Not detected UG/LHighest single sampleEntry point | 5 UG/LMCL | None detected |
| Ethylbenzene | Not detected UG/LHighest single sampleSource water | 300 UG/LMCL | None detected |
| Simazine | Not detected UG/LHighest single sampleSource water | 4 UG/LMCL | None detected |
| Toluene | Not detected UG/LHighest single sampleEntry point | 150 UG/LMCL | None detected |
| XylenesA group of industrial solvents found in gasoline and paint. | Not detected UG/LHighest single sampleSource water | 1750 UG/LMCL | None detected |
Source: Contra Costa Water District, CA's 2024 Consumer Confidence Report — the annual drinking-water report every U.S. utility is required to publish. The numbers on this page are the utility's own. A water-quality report covers an entire service area, not a single address.
People also ask about Contra Costa Water District, CA's water
+Is Contra Costa Water District, CA tap water safe to drink in 2024?
The 2024 Consumer Confidence Report for the Contra Costa Water District, CA water utility lists 4 contaminants at or above the federal limit: Chlorite, Odor, Iron, and Turbidity. 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 Contra Costa Water District, CA tap water?
103 contaminants were measured in Contra Costa Water District, CA's 2024 Consumer Confidence Report, spanning other, metals, and vocs & pesticides. 83 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 Contra Costa Water District, CA tap water?
4 contaminants in Contra Costa Water District, CA's 2024 report sit at or above the federal limit: Chlorite (4.0× the limit); Odor (1.9× the limit); Iron (1.4× the limit); Turbidity (1.3× 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 Contra Costa Water District, CA tap water?
The contaminant with the highest measured value relative to its federal limit in the 2024 report is Chlorite, at 4.0× the federal threshold. It belongs to the disinfection byproducts family of contaminants.
+Are any contaminants in Contra Costa Water District, CA tap water approaching the federal limit?
One contaminant is between 80% and 100% of the federal limit in this report: Color. 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 Contra Costa Water District, 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 Contra Costa Water District, 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.
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