Sun Prairie, WI vs Green Bay, WI

When comparing tap water quality between Sun Prairie, WI and Green Bay, WI, Sun Prairie currently holds a substantial 27-point lead in average WaterQ score, with a score of 78 out of 100 versus 51 for Green Bay. Sun Prairie, WI carries a B grade while Green Bay, WI carries a D. 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.

Green Bay, WI is the larger of the two, with 125,407 more residents than Sun Prairie. Green Bay is served by 4 public water systems, compared with 1 in Sun Prairie — a difference of 3 systems. A larger number of systems often reflects a more fragmented distribution network spanning multiple utilities, suburbs, or rural service areas, while a single large utility serving a big population can benefit from economies of scale in treatment and monitoring, but may also face more complex, aging infrastructure to maintain.

For residents of either Sun Prairie or Green Bay, 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 Sun Prairie or Green Bay 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.