County Water Quality Report

King County, Washington

15 public water systems serving 3,466,590 residents

Data sources: EPA SDWIS EPA ECHO EWG Tap Water Database Utility CCRs ⓘ How did we get these ratings?
County average grade
D
61/100
Utilities rated 15
Population served 3,466,590
Most recent test 2024

Top water quality concerns in King County

  • Haloacetic acids (HAA9) significantly above health guidelinein 12 of 15 utilities
  • Haloacetic acids (HAA5) significantly above health guidelinein 8 of 15 utilities
  • Total trihalomethanes (TTHMs) significantly above health guidelinein 8 of 15 utilities
  • PFAS contaminationin 6 of 15 utilities
  • Arsenic significantly above health guidelinein 4 of 15 utilities

All utilities in King County

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

C
69/100

RENTON CITY OF

Renton · 108,091 residents

Top concern: Haloacetic acids (HAA9) significantly above health guideline

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C
68/100

City of Seattle Water Department

Seattle · 753,000 residents

Top concern: Lead detected in source water

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C
68/100

Auburn City of

Auburn · 107,655 residents

Top concern: Arsenic significantly above health guideline

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C
67/100

SOOS CREEK WATER & SEWER DISTRICT

Renton · 64,534 residents

Top concern: Haloacetic acids (HAA9) significantly above health guideline

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C
67/100

NORTHSHORE UTILITY DISTRICT

Kenmore · 99,789 residents

Top concern: Haloacetic acids (HAA9) significantly above health guideline

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C
67/100

WOODINVILLE WATER DISTRICT

Woodinville · 66,699 residents

Top concern: Haloacetic acids (HAA9) significantly above health guideline

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C
67/100

KIRKLAND CITY OF

Kirkland · 69,243 residents

Top concern: Haloacetic acids (HAA9) significantly above health guideline

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C
67/100

SEATTLE PUBLIC UTILITIES

Seattle · 1,161,961 residents

Top concern: Haloacetic acids (HAA9) significantly above health guideline

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D
62/100

BELLEVUE CITY OF

Bellevue · 321,349 residents

Top concern: Arsenic significantly above health guideline

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D
61/100

REDMOND WATER SYSTEM CITY OF

Redmond · 163,335 residents

Top concern: PFAS contamination

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F
50/100

KENT WATER DEPARTMENT

Kent · 166,421 residents

Top concern: PFAS contamination

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F
50/100

HIGHLINE WATER DISTRICT

Kent · 100,170 residents

Top concern: PFAS contamination

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F
50/100

SAMMAMISH PLATEAU WATER & SEWER

Sammamish · 79,362 residents

Top concern: PFAS contamination

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F
50/100

COVINGTON WATER DISTRICT

Kent · 56,172 residents

Top concern: PFAS contamination

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F
47/100

LAKEHAVEN WATER AND SEWER DISTRICT

FEDERAL WAY · 148,809 residents

Top concern: PFAS contamination

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