States › Washington › King County

King County, WA Water Quality

Water quality data for 43 public water systems serving King County, Washington — based on EPA SDWIS enforcement records, lead testing results, and health-based violation history.

📅 2026 Report 🔄 Data updated 2026 Q2 📍 43 water systems · 62 cities
✅
Excellent — All Systems Performing Well

Water quality across the county is outstanding with minimal violations and very low lead levels.

A

King County Earns a A

King County: 62 communities across 43 water systems. 100.0% have no open violations.

  • Median lead where detected: 1.55 ppb
  • 36 communities with a lead detection, 9 reporting none detected
  • 6 communities with PFAS above the federal limit
  • 9 with significant inspection deficiencies
  • 100.0% of communities have no open violations
1.55 ppb
Median Lead Level
County-wide, 90th percentile
43
Water Systems
Active CWS & NTNCWS
100%
Violation-Free
No active violations on record
How we grade counties: MyWaterIQ uses EPA SDWIS enforcement data — actual MCL violations and lead test results — not the aspirational MCLG targets used by some sites. A grade reflects real compliance history, not theoretical risk. Learn more →

Cities by Water Quality

⭐ Best Performing
  • Bellevue
    Not reported
    No federal limits exceeded on record
    B
  • Redmond
    2.00 ppb
    No federal limits exceeded on record
    A
  • Kirkland
    Not reported
    No federal limits exceeded on record
    B
  • Des Moines
    1.40 ppb
    No federal limits exceeded on record
    A
  • SeaTac
    1.40 ppb
    No federal limits exceeded on record
    A
⚠ Needs Attention
  • Sammamish
    1.70 ppb
    PFAS above the limit at 1 of 7 sampling points
    D
  • Covington
    1.40 ppb
    PFAS above the limit at 1 of 3 sampling points
    D
  • Maple Valley
    1.40 ppb
    PFAS above the limit at 1 of 3 sampling points
    D
  • Lake Morton-Berrydale
    1.40 ppb
    PFAS above the limit at 1 of 3 sampling points
    D
  • Lake Holm
    1.40 ppb
    PFAS above the limit at 1 of 3 sampling points
    D
County Lead Level — Median 1.55 ppb
Based on most recent 90th percentile lead tests across all reporting systems
0 ppb5 ppb10 ppb15 ppb
County median: 1.55 ppb — 10.3% of the federal action level
Systems by Lead Level
Under 5 ppb
33
5 – 10 ppb
1
10 – 15 ppb
2
No Data
26

All Cities in King County

Seattle 1.60 ppb A
Bellevue Not reported B
Federal Way 3.30 ppb A
Kent Not detected B
Redmond 2.00 ppb A
Auburn 2.20 ppb C
Renton 1.90 ppb B
Sammamish 1.70 ppb D
Kirkland Not reported B
Shoreline 1.60 ppb A
Issaquah 1.00 ppb A
Des Moines 1.40 ppb A
SeaTac 1.40 ppb A
Mercer Island Not reported B
Burien Not reported B
Kenmore 36.00 ppb C
Cottage Lake Not reported B
Covington 1.40 ppb D
Bothell 28.00 ppb C
Maple Valley 1.40 ppb D
White Center 1.60 ppb A
Snoqualmie 2.50 ppb A
Lakeland South 3.30 ppb A
Woodinville Not reported B
Newcastle Not reported B
Enumclaw 1.50 ppb A
Tukwila Not reported B
East Renton Highlands 1.20 ppb A
Bryn Mawr-Skyway Not detected A
Lakeland North 3.30 ppb A
Lake Morton-Berrydale 1.40 ppb D
Union Hill-Novelty Hill 2.00 ppb A
Fairwood Not reported B
Duvall Not reported B
Pacific Not detected B
Hobart Not detected A
Lake Forest Park Not reported B
Normandy Park 1.40 ppb A
North Bend Not detected A
Boulevard Park Not reported B
Vashon 3.00 ppb A
Lake Holm 1.40 ppb D
Maple Heights-Lake Desire Not detected A
Algona Not detected B
Clyde Hill Not reported B
Black Diamond 1.50 ppb B
Mirrormont 1.50 ppb B
Medina Not reported B
Carnation 1.90 ppb B
Fall City 1.00 ppb B
Shadow Lake Not detected A
Wilderness Rim 1.70 ppb B
Lake Marcel-Stillwater Not reported B
Ames Lake 1.00 ppb B
Riverbend 1.00 ppb B
Riverpoint Not detected A
Yarrow Point Not reported B
Ravensdale 1.40 ppb D
Hunts Point Not reported B
Beaux Arts Village 0.90 ppb B
Skykomish 0.90 ppb B
Baring 6.50 ppb B
Showing 62 cities
No active violations Active violations

About King County Drinking Water

King County is served by 43 water systems covering 62 communities. No community here has an open violation on record.

Of the communities reporting lead results, 36 recorded a detection, with a median of 1.55 ppb — 10% of the federal action level. 9 reported none detected, which means below the laboratory limit rather than an absence of lead.

6 of 62 communities have PFAS above the limits EPA set in 2024, measured as a running annual average at each sampling point. State inspectors recorded significant deficiencies at 9 of them.

Frequently Asked Questions

Is King County tap water safe to drink?▼
No community in King County has an open violation on record. 6 of 62 have PFAS above the federal limit, which is the main open concern.
What is the lead level in King County?▼
Among communities with a detection the median is 1.55 ppb, 10% of the 15 ppb action level. 9 reported none detected and 17 reported no result.
How many water systems serve King County?▼
43 community water systems serve 62 communities here.
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