Kailua-Kona, HI vs Hilo, HI

When comparing tap water quality between Kailua-Kona, HI and Hilo, HI, Kailua-Kona currently holds a noticeable 9-point lead in average WaterQ score, with a score of 100 out of 100 versus 91 for Hilo. Both cities currently carry an A grade overall. 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.

Hilo, HI is the larger of the two, with 112,976 more residents than Kailua-Kona. Hilo is served by 15 public water systems, compared with 1 in Kailua-Kona — a difference of 14 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 Kailua-Kona or Hilo, 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 Kailua-Kona or Hilo 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.