Loading water data...
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 1,634,276 residents
Santa Clara County in California has an average water quality score of 93/100 (Grade A) based on analysis of 8 municipal water systems. The county's water systems serve approximately 1,634,276 residents.
Overall, Santa Clara County demonstrates good water quality standards. 6 of 8 cities exceed the county average, with Cupertino leading with a score of 100/100.
8 cities ranked by water quality score
| Rank | City | Score | Grade | Population |
|---|---|---|---|---|
| 1 | Sunnyvale | 100 | A | 157,566 |
| 2 | Santa Clara | 100 | A | 130,746 |
| 3 | Mountain View | 100 | A | 81,501 |
| 4 | Palo Alto | 100 | A | 67,231 |
| 5 | Cupertino | 100 | A | 16,336 |
| 6 | Milpitas Biggest deduction: 2 monitoring/reporting violations in the last 5 years (−2 pts) | 98 | A | 81,773 |
| 7 | San Jose Biggest deduction: 1 health-based violation (MCL/treatment-technique) in the last 5 years (−10 pts) | 78 | C | 1,039,920 |
| 8 | Gilroy Biggest deduction: 1 health-based violation (MCL/treatment-technique) in the last 5 years (−10 pts) | 64 | D | 59,203 |
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) | 1.775 ppt | 8 ppt | 4 ppt | 44.4% | 8 |
| TTHM (2012–2019 avg) | 34.688 ug/L | 47.727 ug/L | 80 ug/L | 43.4% | 7 |
| HAA5 (2012–2019 avg) | 21.116 ug/L | 34.807 ug/L | 60 ug/L | 35.2% | 7 |
| Fluoride (2012–2019 avg) | 0.465 mg/L | 0.76 mg/L | 4 mg/L | 11.6% | 2 |
| Lead (90th percentile) | 0.9 ppb | 2.7 ppb | 15 ppb | 6% | 8 |
| Uranium (2012–2019 avg) | 0.598 ug/L | 1.196 ug/L | 30 ug/L | 2% | 2 |
| Nitrate (2012–2019 avg) | 0.057 mg/L | 0.057 mg/L | 10 mg/L | 0.6% | 1 |
| Arsenic (2012–2019 avg) | 0 ug/L | 0 ug/L | 10 ug/L | 0% | 1 |
Recent violations across county water systems
Water quality in Santa Clara 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 1,634,276 residents.
The county shows strong water quality performance, with scores ranging from 64/100 in Gilroy to 100/100 in Cupertino. This 36-point spread indicates significant variation in water quality across the county, suggesting different water sources or treatment approaches.
The most prevalent contaminants detected across Santa Clara County water systems include PFAS (PFOA/PFOS max, UCMR5), TTHM (2012–2019 avg), HAA5 (2012–2019 avg). Every county-wide average sits below 50% of its EPA Maximum Contaminant Level (MCL).
Santa Clara 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.
Santa Clara County has an average water quality score of 93/100 (Grade A) based on analysis of 8 municipal water systems serving 1,634,276 residents.
Cupertino has the highest water quality score in Santa Clara County at 100/100. View the detailed report for Cupertino.
Most cities in Santa Clara 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.