Philadelphia, PA vs Herndon, VA

When comparing tap water quality between Philadelphia, PA and Herndon, VA, Herndon currently holds a substantial 15-point lead in average WaterQ score, with a score of 97 out of 100 versus 82 for Philadelphia. Philadelphia, PA carries a B grade while Herndon, VA carries an A. A WaterQ score reflects an aggregate of EPA-reported violations, monitoring data, and compliance history across all public water systems serving each city, so a higher score generally indicates fewer recent violations and a stronger compliance record, though it does not guarantee that every tap in the city tests identically.

Philadelphia, PA is the larger of the two, with 454,786 more residents than Herndon, yet both cities are served by the same number of public water systems (2). This means the difference in population is handled by systems of different scale rather than a different count of utilities — larger systems generally serve more connections and may have more monitoring requirements under the Safe Drinking Water Act.

For residents of either Philadelphia or Herndon, the most useful next step is to look up the specific water system that serves your address, since city-wide averages combine results from every system in the area. Visit the Philadelphia or Herndon city pages below for a breakdown of local systems, recent violations, and contaminant-specific data, or browse WaterQ's contaminants directory to learn what each measured substance means for health.