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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 6 cities serving 2,185,633 residents
Alameda County in California has an average water quality score of 90/100 (Grade A) based on analysis of 6 municipal water systems. The county's water systems serve approximately 2,185,633 residents.
Overall, Alameda County demonstrates good water quality standards. 4 of 6 cities exceed the county average, with Dublin leading with a score of 100/100.
6 cities ranked by water quality score
| Rank | City | Score | Grade | Population |
|---|---|---|---|---|
| 1 | Fremont | 100 | A | 344,000 |
| 2 | Hayward | 100 | A | 162,954 |
| 3 | Dublin | 100 | A | 98,776 |
| 4 | Oakland Biggest deduction: Other PFAS detected in UCMR5 sampling: PFHxA 3.5 ppt, PFBA 5.2 ppt (−4 pts) | 96 | A | 1,442,800 |
| 5 | Pleasanton Biggest deduction: PFOA detected at up to 5.1 ppt in UCMR5 sampling (2025-05-15), at or above EPA's 4 ppt MCL (−10 pts) | 74 | C | 76,689 |
| 6 | Livermore Biggest deduction: PFOA detected at up to 4.8 ppt in UCMR5 sampling (2024-07-16), at or above EPA's 4 ppt MCL (−10 pts) | 68 | D | 60,414 |
Real EPA readings across county water systems (lead: latest 90th percentile; PFAS: UCMR5 2023–2026; others: 2012–2019 averages)
| Contaminant | Avg Level | Max Level | EPA Limit | % of Limit | Cities |
|---|---|---|---|---|---|
| PFAS (PFOA/PFOS max, UCMR5) | 6.333 ppt | 26 ppt | 4 ppt | 158.3% | 6 |
| Fluoride (2012–2019 avg) | 0.801 mg/L | 0.862 mg/L | 4 mg/L | 20% | 2 |
| Nitrate (2012–2019 avg) | 1.903 mg/L | 5.24 mg/L | 10 mg/L | 19% | 3 |
| TTHM (2012–2019 avg) | 13.921 ug/L | 23.116 ug/L | 80 ug/L | 17.4% | 4 |
| HAA5 (2012–2019 avg) | 9.02 ug/L | 12.642 ug/L | 60 ug/L | 15% | 4 |
| Lead (90th percentile) | 1.25 ppb | 7.5 ppb | 15 ppb | 8.3% | 6 |
| Arsenic (2012–2019 avg) | 0.277 ug/L | 0.831 ug/L | 10 ug/L | 2.8% | 3 |
| Uranium (2012–2019 avg) | 0.247 ug/L | 0.493 ug/L | 30 ug/L | 0.8% | 2 |
Water quality in Alameda County, California reflects the region's unique combination of water sources, treatment infrastructure, and environmental factors. Our comprehensive analysis examines 6 municipal water systems serving a combined population of over 2,185,633 residents.
The county shows strong water quality performance, with scores ranging from 68/100 in Livermore to 100/100 in Dublin. This 32-point spread indicates significant variation in water quality across the county, suggesting different water sources or treatment approaches.
The most prevalent contaminants detected across Alameda County water systems include PFAS (PFOA/PFOS max, UCMR5), Fluoride (2012–2019 avg), Nitrate (2012–2019 avg). At least one reading averages above 50% of its EPA limit across the county's systems, worth attention from residents and utilities.
Alameda County's water quality is generally good. Residents can feel confident in their tap water quality, though those with specific health concerns or sensitivity to certain contaminants may still benefit from filtration. Regular review of your city's annual Consumer Confidence Report is recommended.
Alameda County has an average water quality score of 90/100 (Grade A) based on analysis of 6 municipal water systems serving 2,185,633 residents.
Dublin has the highest water quality score in Alameda County at 100/100. View the detailed report for Dublin.
Most cities in Alameda County have water that meets EPA standards. However, a water filter can provide additional protection and improve taste. The need depends on your specific city and any personal health considerations.
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.