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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 13 cities serving 2,701,015 residents
San Diego County in California has an average water quality score of 76/100 (Grade B) based on analysis of 13 municipal water systems. The county's water systems serve approximately 2,701,015 residents.
Water quality in San Diego County is fair, with some cities showing room for improvement. 5 cities have scores below 70, indicating elevated contaminant levels that residents should be aware of. San Diego has the best water quality at 96/100.
13 cities ranked by water quality score
| Rank | City | Score | Grade | Population |
|---|---|---|---|---|
| 1 | San Diego Top concern: Fluoride (18.1% of limit) | 96 | A+ | 1,387,088 |
| 2 | Escondido Top concern: Haloacetic Acids (19.2% of limit) | 90 | A | 146,452 |
| 3 | Oceanside Top concern: Total Trihalomethanes (40.7% of limit) | 85 | A- | 179,006 |
| 4 | La Mesa Top concern: Fluoride (17% of limit) | 85 | A- | 58,925 |
| 5 | Vista Top concern: Copper (14.2% of limit) | 83 | B+ | 100,396 |
| 6 | Chula Vista Top concern: Total Trihalomethanes (26.6% of limit) | 82 | B+ | 274,793 |
| 7 | Santee Top concern: Haloacetic Acids (42% of limit) | 81 | B+ | 63,859 |
| 8 | El Cajon Top concern: Total Trihalomethanes (36.7% of limit) | 77 | B | 101,327 |
| 9 | National City Top concern: Total Trihalomethanes (68.6% of limit) | 69 | C+ | 58,660 |
| 10 | Poway Top concern: Haloacetic Acids (40.4% of limit) | 69 | C+ | 51,378 |
| 11 | Carlsbad Top concern: Haloacetic Acids (71.2% of limit) | 66 | C+ | 112,923 |
| 12 | Encinitas Top concern: Lead (66.3% of limit) | 56 | C- | 66,157 |
| 13 | San Marcos Top concern: Total Trihalomethanes (65.4% of limit) | 45 | F | 100,051 |
Top detected contaminants across county water systems
| Contaminant | Avg Level | Max Level | EPA Limit | % of Limit | Cities |
|---|---|---|---|---|---|
| Haloacetic Acids | 18.049 ug/L | 42.707 ug/L | 60 ug/L | 30.1% | 13 |
| Total Trihalomethanes | 24.035 ug/L | 54.872 ug/L | 80 ug/L | 30% | 11 |
| Lead | 0.004 mg/L | 0.01 mg/L | 0.015 mg/L | 23.6% | 12 |
| Chromium | 0.023 mg/L | 0.046 mg/L | 0.1 mg/L | 22.9% | 12 |
| Fluoride | 0.907 mg/L | 1.483 mg/L | 4 mg/L | 22.7% | 12 |
| Copper | 0.286 mg/L | 0.669 mg/L | 1.3 mg/L | 22% | 11 |
| Mercury | 0 mg/L | 0.001 mg/L | 0.002 mg/L | 19.5% | 11 |
| Arsenic | 0.002 mg/L | 0.004 mg/L | 0.01 mg/L | 18.5% | 13 |
Recent violations across county water systems
Showing 10 of 20 recent violations
Water quality in San Diego County, California reflects the region's unique combination of water sources, treatment infrastructure, and environmental factors. Our comprehensive analysis examines 13 municipal water systems serving a combined population of over 2,701,015 residents.
The county shows moderate water quality performance, with scores ranging from 45/100 in San Marcos to 96/100 in San Diego. This 51-point spread indicates significant variation in water quality across the county, suggesting different water sources or treatment approaches.
The most prevalent contaminants detected across San Diego County water systems include Haloacetic Acids, Total Trihalomethanes, Lead. All monitored contaminants remain within acceptable levels relative to EPA Maximum Contaminant Levels (MCLs).
Water quality in San Diego 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.
San Diego County has an average water quality score of 76/100 (Grade B) based on analysis of 13 municipal water systems serving 2,701,015 residents.
San Diego has the highest water quality score in San Diego County at 96/100. View the detailed report for San Diego.
Given the water quality variation across San Diego County, we recommend reviewing your specific city's water quality report. 5 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.