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Not health advice. Contact your local water utility for concerns.
Data from EPA Water Quality Reports. For official information, contact your water utility or health department.
Water quality data for 8 cities serving 698,239 residents
Contra Costa County in California has an average water quality score of 79/100 (Grade B) based on analysis of 8 municipal water systems. The county's water systems serve approximately 698,239 residents.
Water quality in Contra Costa County is fair, with some cities showing room for improvement. 2 cities have scores below 70, indicating elevated contaminant levels that residents should be aware of. Pittsburg has the best water quality at 89/100.
8 cities ranked by water quality score
| Rank | City | Score | Grade | Population |
|---|---|---|---|---|
| 1 | Pittsburg Top concern: Total Trihalomethanes (19.4% of limit) | 89 | A- | 76,804 |
| 2 | Richmond Top concern: Total Trihalomethanes (18.7% of limit) | 86 | A- | 110,612 |
| 3 | Walnut Creek Top concern: Total Trihalomethanes (21.8% of limit) | 85 | A- | 66,512 |
| 4 | San Ramon Top concern: Fluoride (15.1% of limit) | 84 | B+ | 86,920 |
| 5 | Danville Top concern: Total Trihalomethanes (36.8% of limit) | 82 | B+ | 41,034 |
| 6 | Brentwood Top concern: Total Trihalomethanes (38% of limit) | 72 | B- | 62,290 |
| 7 | Concord Top concern: Copper (33.5% of limit) | 68 | C+ | 133,984 |
| 8 | Antioch Top concern: Total Trihalomethanes (72.3% of limit) | 65 | C+ | 120,083 |
Top detected contaminants across county water systems
| Contaminant | Avg Level | Max Level | EPA Limit | % of Limit | Cities |
|---|---|---|---|---|---|
| Total Trihalomethanes | 23.72 ug/L | 57.842 ug/L | 80 ug/L | 29.6% | 7 |
| Copper | 0.294 mg/L | 0.607 mg/L | 1.3 mg/L | 22.7% | 8 |
| Haloacetic Acids | 12.642 ug/L | 19.317 ug/L | 60 ug/L | 21.1% | 6 |
| Lead | 0.003 mg/L | 0.005 mg/L | 0.015 mg/L | 18.7% | 7 |
| Chromium | 0.017 mg/L | 0.048 mg/L | 0.1 mg/L | 16.8% | 7 |
| Fluoride | 0.613 mg/L | 0.706 mg/L | 4 mg/L | 15.3% | 4 |
| Nitrite | 0.147 mg/L | 0.423 mg/L | 1 mg/L | 14.7% | 7 |
| Mercury | 0 mg/L | 0.001 mg/L | 0.002 mg/L | 14.4% | 8 |
Recent violations across county water systems
Showing 10 of 20 recent violations
Water quality in Contra Costa County, California reflects the region's unique combination of water sources, treatment infrastructure, and environmental factors. Our comprehensive analysis examines 8 municipal water systems serving a combined population of over 698,239 residents.
The county shows moderate water quality performance, with scores ranging from 65/100 in Antioch to 89/100 in Pittsburg. This 24-point spread indicates significant variation in water quality across the county, suggesting different water sources or treatment approaches.
The most prevalent contaminants detected across Contra Costa County water systems include Total Trihalomethanes, Copper, Haloacetic Acids. All monitored contaminants remain within acceptable levels relative to EPA Maximum Contaminant Levels (MCLs).
Water quality in Contra Costa County is fair but shows room for improvement. Residents in cities scoring below 70 should consider water filtration, particularly for drinking and cooking. Check your specific city's report above for personalized recommendations.
Contra Costa County has an average water quality score of 79/100 (Grade B) based on analysis of 8 municipal water systems serving 698,239 residents.
Pittsburg has the highest water quality score in Contra Costa County at 89/100. View the detailed report for Pittsburg.
Given the water quality variation across Contra Costa County, we recommend reviewing your specific city's water quality report. 2 cities have scores below 70, where filtration is particularly recommended.
Click on any city in the rankings table above to view its detailed water quality report, including contaminant levels, EPA compliance history, and filter recommendations.