County Water Quality Report

Honolulu County, Hawaii

4 public water systems serving 1,259,098 residents

Data sources: EPA SDWIS EPA ECHO EWG Tap Water Database Utility CCRs ⓘ How did we get these ratings?
County average grade
C
72/100
Utilities rated 4
Population served 1,259,098
Most recent test 2024

Top water quality concerns in Honolulu County

  • Chromium (hexavalent) significantly above health guidelinein 3 of 4 utilities
  • Total trihalomethanes (TTHMs) significantly above health guidelinein 2 of 4 utilities
  • Perfluorohexane sulfonate (PFHXS) significantly above health guidelinein 1 of 4 utilities
  • 1,2,3-Trichloropropane significantly above health guidelinein 1 of 4 utilities
  • Nitrate significantly above health guidelinein 1 of 4 utilities

All utilities in Honolulu County

Click any utility for full grade card, contaminant data, and treatment plant contact info.

B
80/100

JOINT BASE PEARL HARBOR-HICKAM

PEARL HARBOR · 65,230 residents

Top concern: Chromium (hexavalent) significantly above health guideline

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C
74/100

WAIPAHU-EWA-WAIANAE

WAIPAHU-EWA-WAIANAE · 217,479 residents

Top concern: Chromium (hexavalent) significantly above health guideline

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C
72/100

HNL-WINDWARD-PEARL HARBOR

HONOLULU-WINDWARD-PEARLHARBOR · 631,389 residents

Top concern: Chromium (hexavalent) significantly above health guideline

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D
64/100

Honolulu Municipal Water System

Honolulu · 345,000 residents

Top concern: Arsenic significantly above health guideline

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