King County Water District No 90
EPA ID: WA5341150 · 20,100 people served · 8 ZIP codes
Water monitoring for King County Water District No 90: clean, five years, 20,100 residents.
Data: EPA SDWIS Last verified: 2026-04-02
Service Area Map
Coverage area for King County Water District No 90 Source: EPA SDWIS service area boundaries.
Service area boundary
Service Area Demographics
The King County Water District No 90 serves a community with a median household income of $122,691 and an estimated 264,466 residents across its service area. Approximately 48% of housing stock was built before 1986, which increases the likelihood of lead service lines and older plumbing.
🌊 Where Does Your Water Come From?
King County Water District No 90's water is drawn from rivers, lakes, or reservoirs. Surface water sources are more exposed to agricultural runoff, stormwater, and upstream discharges, but they typically receive more intensive treatment before reaching your tap.
About 2% of homes in King County, Washington rely on private wells rather than public water systems. Private well owners are responsible for their own water testing and treatment.
Superfund Proximity Note: This service area ranks in the 70th percentile nationally for proximity to Superfund (NPL) sites.
Infrastructure Risk
PFAS Detected in Service Area
PFAS ("forever chemicals") have been detected in water serving this system's area. 12 detections recorded. 1 exceeds federal EPA limits (4 ppt for PFOA/PFOS).
Comparable Water Systems
Similar-sized systems in Washington
Estimated Remediation Costs
Average estimated costs across ZIP codes served by this system
Based on national averages for common remediation projects. Actual costs vary by property. Only issues flagged by EPA, FEMA, or state data for each ZIP code are included.
System Overview
King County Water District No 90 (EPA ID: WA5341150) is a community water system in Washington that serves approximately 20,100 people from surface water sources.
This system provides water to 8 ZIP codes across 4 communities.
Violation History
Lead & Copper
No Lead and Copper Rule sampling data available for this water system.
Need help with your water quality?
Typical cost: Water test: typically $20–$50 (DIY kit) · Professional inspection: $150–$400
Find the Right Water FilterFree tip: Let cold water run for 2 minutes before drinking — this helps flush lead from your pipes.
ZIP Codes Served
Coverage: 5 ZIP codes confirmed via EPA Community Water System Service Area Boundaries v3 plus 3 additional ZIPs inferred from SDWIS registry data. The EPA-confirmed set is the most reliable; SDWIS-inferred entries may be narrower than the real deployment area.
- 98006 — Bellevue
- 98027 — Issaquah
- 98038 — Maple Valley
- 98055 — Renton
- 98056 — Renton
- 98057 — Renton
- 98058 — Renton
- 98059 — Renton
Data Sources
This report uses public data from the EPA Safe Drinking Water Information System (SDWIS). View the full compliance record for King County Water District No 90 (WA5341150) on EPA.gov.
Frequently Asked Questions
Is King County Water District No 90 water safe to drink?
Based on EPA records, King County Water District No 90 has no recorded violations in the past 5 years — a positive indicator of water quality management.
How many people does King County Water District No 90 serve?
King County Water District No 90 serves approximately 20,100 people across 8 ZIP codes in Washington.
Where does King County Water District No 90 get its water?
The primary water source is surface water.
Federal UCMR5 PFAS Monitoring: Tested Clean
This water system was tested under the federal EPA Unregulated Contaminant Monitoring Rule (UCMR5). No PFAS compounds were detected.
Current MCL reflects the lowest state-enforceable limit (NYS 10 ppt for PFOA/PFOS, effective August 2020). The federal final MCL of 4 ppt for PFOA/PFOS (EPA April 2024 rule) is not enforceable until April 2029. Detections above 4 ppt but below 10 ppt are below current MCL but above the future federal limit.
Source: U.S. EPA UCMR5 (Unregulated Contaminant Monitoring Rule, 5th cycle) — per-system federal sampling, 2023–2025. EPA UCMR5 monitoring program →
Lead Service Line Inventory
Service line breakdown reported under the federal Lead and Copper Rule Improvements (LCRI) inventory requirement:
This system reports zero confirmed lead service lines in its inventory. Unknown-material counts may still warrant verification.
Federal LCRI rule (effective October 2024) requires every public water system to inventory its service lines and complete lead-line replacement within 10 years.
Source: EPA SDWIS Federal Service Line Inventory (Phase 2) · Submitted 2026
ZipCheckup is not affiliated with the utility or state agency. Inventory figures render verbatim from the public LCRI submission cited above; ZipCheckup does not perform inspections or replacements.