All Data Provided by EWG
Contra Costa Water District
EWG’s drinking water quality report shows results of tests conducted by the water utility and provided to the Environmental Working Group by the California State Water Resources Control Board, as well as information from the U.S. EPA Enforcement and Compliance History database (ECHO). For the latest quarter assessed by the U.S. EPA (January 2021 – March 2021), tap water provided by this water utility was in compliance with federal health based drinking water standards.
Utility Details
Serves: 198,000
Data available: 2013 2019*
Source: Surface water
* 2013 testing is for chemicals in EPA’s Third Unregulated Contaminant Monitoring Rule (UCMR 3) only.
Contaminants Detected
13 EXCEED EWG HEALTH GUIDELINES
26 Total Contaminants
- Legal does not necessarily equal safe. Getting a passing grade from the federal government does not mean the water meets the latest health guidelines.
- Legal limits for contaminants in tap water have not been updated in almost 20 years.
- The best way to ensure clean tap water is to keep pollution out of source water in the first place.
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Contaminants Detected
Bromate
Potential Effect: cancer
10x
EWG’S HEALTH GUIDELINE
Bromochloroacetic acid
Potential Effect:
133x
EWG’S HEALTH GUIDELINE
Bromodichloromethane
Potential Effect: cancer
87x
EWG’S HEALTH GUIDELINE
Bromoform
Potential Effect: cancer
5x
EWG’S HEALTH GUIDELINE
Chloroform
Potential Effect: cancer
12x
EWG’S HEALTH GUIDELINE
Chromium (hexavalent)
Potential Effect: cancer
3.2x
EWG’S HEALTH GUIDELINE
Dibromoacetic acid
Potential Effect: cancer
43x
EWG’S HEALTH GUIDELINE
Dibromochloromethane
Potential Effect: cancer
54x
EWG’S HEALTH GUIDELINE
Dichloroacetic acid
Potential Effect: cancer
18x
EWG’S HEALTH GUIDELINE
Haloacetic acids (HAA5)†
Potential Effect: cancer
60x
EWG’S HEALTH GUIDELINE
Haloacetic acids (HAA9)†
Potential Effect: cancer
186x
EWG’S HEALTH GUIDELINE
Total trihalomethanes (TTHMs)†
Potential Effect: cancer
126x
EWG’S HEALTH GUIDELINE
Trichloroacetic acid
Potential Effect: cancer
3.8x
EWG’S HEALTH GUIDELINE
Other Contaminants Tested
Contra Costa Water District compliance with legally mandated federal standards:
- From April 2019 to March 2021, Contra Costa Water District complied with health based drinking water standards.
| Contaminant | Activated Carbon | Reverse Osmosis | Ion Exchange |
| CONTAMINANTS ABOVE HEALTH GUIDELINES | |||
| Bromate | ✔ | ✔ | ✔ |
| Bromochloroacetic acid | ✔ | ✔ | |
| Bromodichloromethane | ✔ | ✔ | |
| Bromoform | ✔ | ✔ | |
| Chloroform | ✔ | ✔ | |
| Chromium (hexavalent) | ✔ | ✔ | |
| Dibromoacetic acid | ✔ | ✔ | |
| Dibromochloromethane | ✔ | ✔ | |
| Dibromoacetic acid | ✔ | ✔ | |
| Haloacetic acids (HAA5) | ✔ | ✔ | |
| Haloacetic acids (HAA9) | ✔ | ✔ | |
| Total trihalomethanes (TTHMs) | ✔ | ✔ | |
| Trichloroacetic acid | ✔ | ✔ | |
| OTHER CONTAMINANTS DETECTED | |||
| Aluminum | ✔ | ||
| Bromide | ✔ | ✔ | |
| Bromochloromethane | ✔ | ✔ | |
| Chlorate | |||
| Chromium (total) | ✔ | ✔ | |
| Fluoride | ✔ | ||
| Manganese | ✔ | ||
| Molybdenum | ✔ | ✔ | ✔ |
| Nitrate | ✔ | ✔ | |
| Nitrate & nitrite | ✔ | ✔ | |
| Strontium | ✔ | ✔ | |
| Vanadium | ✔ |
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