What was found in Concord's water
The level at the city's main supplier, the highest level anywhere in the city, the EPA limit for each, and where every figure comes from.
| Contaminant | Level vs EPA limit | Suppliers | Source |
|---|---|---|---|
| Nitrate | 1288.2 µg/L 13% of the EPA limit 10000 µg/L Main supplier: CONTRA COSTA WATER DISTRICT · 198,000 people · 2019
Highest in the city: 1352.61 µg/L — RANDALL-BOLD WATER TREATMENT PLANT · 1 people · 2019 | 3/3 | SYR4 |
| Fluoride | 800 µg/L 20% of the EPA limit 4000 µg/L Main supplier: CONTRA COSTA WATER DISTRICT · 198,000 people · 2019
Highest in the city: 1000 µg/L — RANDALL-BOLD WATER TREATMENT PLANT · 1 people · 2019 | 3/3 | SYR4 |
| Nitrate-Nitrite | 920 µg/L 9.2% of the EPA limit 10000 µg/L Main supplier: CONTRA COSTA WATER DISTRICT · 198,000 people · 2019 | 3/3 | SYR4 |
| Nitrite | 494.004 µg/L 49% of the EPA limit 1000 µg/L Main supplier: CONTRA COSTA WATER DISTRICT · 198,000 people · 2019 | 1/3 | SYR4 |
| Copper | 278 µg/L 21% of the EPA limit 1300 µg/L Main supplier: CONTRA COSTA WATER DISTRICT · 198,000 people · 2019 | 1/3 | SYR4 |
| Barium | 160 µg/L 8% of the EPA limit 2000 µg/L Main supplier: CONTRA COSTA WATER DISTRICT · 198,000 people · 2019 | 3/3 | SYR4 |
| TTHM | 39.3 µg/L 49% of the EPA limit 80 µg/L Main supplier: CONTRA COSTA WATER DISTRICT · 198,000 people · 2019
Highest in the city: 66.7 µg/L — CCWD/BRENTWOOD WTP · 0 people · 2019 | 3/3 | SYR4 |
| Gross Beta Particle Activity | 48.2 pCi/L No EPA limit set Main supplier: CONTRA COSTA WATER DISTRICT · 198,000 people · 2019 | 2/3 | SYR4 |
| Selenium | 37.15 µg/L 74% of the EPA limit 50 µg/L Main supplier: CONTRA COSTA WATER DISTRICT · 198,000 people · 2019 | 1/3 | SYR4 |
| Bromoform | 9.37 µg/L No EPA limit set Main supplier: CONTRA COSTA WATER DISTRICT · 198,000 people · 2019
Highest in the city: 32 µg/L — CCWD/BRENTWOOD WTP · 0 people · 2019 | 3/3 | SYR4 |
| Chromium | 29 µg/L 29% of the EPA limit 100 µg/L Main supplier: CONTRA COSTA WATER DISTRICT · 198,000 people · 2019 | 1/3 | SYR4 |
| Dibromochloromethane | 14.1 µg/L No EPA limit set Main supplier: CONTRA COSTA WATER DISTRICT · 198,000 people · 2019
Highest in the city: 25.9 µg/L — CCWD/BRENTWOOD WTP · 0 people · 2019 | 3/3 | SYR4 |
| Chloroform | 9.74 µg/L No EPA limit set Main supplier: CONTRA COSTA WATER DISTRICT · 198,000 people · 2019
Highest in the city: 14.2 µg/L — CCWD/BRENTWOOD WTP · 0 people · 2019 | 3/3 | SYR4 |
| Bromate | 13.3 µg/L 133% of the EPA limit, at the 95th percentile of samples — 10 µg/L Main supplier: CONTRA COSTA WATER DISTRICT · 198,000 people · 2019 | 3/3 | SYR4 |
| Bromodichloromethane | 11.6 µg/L No EPA limit set Main supplier: CONTRA COSTA WATER DISTRICT · 198,000 people · 2019
Highest in the city: 13 µg/L — CCWD/BRENTWOOD WTP · 0 people · 2019 | 3/3 | SYR4 |
| Total Haloacetic Acids (HAA5) | 10.7 µg/L 18% of the EPA limit 60 µg/L Main supplier: CONTRA COSTA WATER DISTRICT · 198,000 people · 2019 | 3/3 | SYR4 |
| Dibromoacetic Acid | 4.625 µg/L No EPA limit set Main supplier: CONTRA COSTA WATER DISTRICT · 198,000 people · 2019
Highest in the city: 6.76 µg/L — CCWD/BRENTWOOD WTP · 0 people · 2019 | 3/3 | SYR4 |
| Dichloroacetic Acid | 6.275 µg/L No EPA limit set Main supplier: CONTRA COSTA WATER DISTRICT · 198,000 people · 2019 | 3/3 | SYR4 |
| Arsenic | 5.845 µg/L 58% of the EPA limit 10 µg/L Main supplier: CONTRA COSTA WATER DISTRICT · 198,000 people · 2019 | 3/3 | SYR4 |
| Trichloroacetic Acid | 3.36 µg/L No EPA limit set Main supplier: CONTRA COSTA WATER DISTRICT · 198,000 people · 2019 | 3/3 | SYR4 |
| Dichloromethane | 2.98 µg/L 60% of the EPA limit 5 µg/L Main supplier: CONTRA COSTA WATER DISTRICT · 198,000 people · 2019
Highest in the city: 3.16 µg/L — CCWD/BRENTWOOD WTP · 0 people · 2019 | 3/3 | SYR4 |
| Lead | 2.66 µg/L 18% of the EPA limit 15 µg/L Main supplier: CONTRA COSTA WATER DISTRICT · 198,000 people · 2019 | 2/3 | SYR4 |
| Monobromoacetic Acid | 2.52 µg/L No EPA limit set Main supplier: CONTRA COSTA WATER DISTRICT · 198,000 people · 2019 | 2/3 | SYR4 |
| Cadmium | 1.595 µg/L 32% of the EPA limit 5 µg/L Main supplier: CONTRA COSTA WATER DISTRICT · 198,000 people · 2019
Highest in the city: 1.6 µg/L — RANDALL-BOLD WATER TREATMENT PLANT · 1 people · 2019 | 3/3 | SYR4 |
| Cyanide | 1.57 µg/L 0.8% of the EPA limit 200 µg/L Main supplier: CONTRA COSTA WATER DISTRICT · 198,000 people · 2019 | 2/3 | SYR4 |
| Combined Uranium | 1.39315 µg/L 4.6% of the EPA limit 30 µg/L Main supplier: CONTRA COSTA WATER DISTRICT · 198,000 people · 2019 | 1/3 | SYR4 |
| Di(2-ethylhexyl) Phthalate | 0.3845 µg/L 6.4% of the EPA limit 6 µg/L Main supplier: CONTRA COSTA WATER DISTRICT · 198,000 people · 2019 | 3/3 | SYR4 |
| Di(2-ethylhexyl) Adipate | 0.2100 µg/L 0.1% of the EPA limit 400 µg/L Main supplier: CONTRA COSTA WATER DISTRICT · 198,000 people · 2019 | 3/3 | SYR4 |
| Asbestos | 0.2000 MFL 2.9% of the EPA limit 7 MFL Main supplier: CONTRA COSTA WATER DISTRICT · 198,000 people · 2019 | 1/3 | SYR4 |
| Lead | 0.0031 mg/L 21% of the EPA limit 0.0150 mg/L Main supplier: CONTRA COSTA WATER DISTRICT · 198,000 people · 2025 | 1/3 | 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.
These are the utilities' own EPA-reported results, not a city-wide
average. A detection means the lab measured the
substance — it isn't the same as exceeding a legal limit. Hover a source
tag to see the EPA program and years behind each figure.
Water suppliers serving Concord
| Supplier | Population served |
|---|---|
| CONTRA COSTA WATER DISTRICT | 198,000 |
| RANDALL-BOLD WATER TREATMENT PLANT | 1 |
| CCWD/BRENTWOOD WTP | 0 |
Frequently asked questions about Concord tap water
Is Concord tap water safe to drink?
EPA testing detected 30 contaminants in the water serving Concord. A detection isn't the same as a violation — most detected levels are within federal limits. Check the level and source for each contaminant above, and your utility's annual Consumer Confidence Report for the official compliance status.
How many water suppliers serve Concord?
3 public water suppliers report drinking-water monitoring for Concord, California to the EPA. Each is listed above with its population served.
What contaminants are in Concord's water?
The contaminants EPA monitoring detected in Concord include Nitrate, Fluoride, Nitrate-Nitrite, Nitrite, Copper. The full list, with the level at the main supplier and the data source, is in the table above.
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.