King County Water District No 90
EPA ID: WA5341150 · 20,100 people served · 5 ZIP codes
ZipCheckup's reading of EPA SDWIS for King County Water District No 90 (WA5341150): 2 EPA violations in the last five years. While 2 violations did appear in King County Water District No 90's five-year monitoring record, none remain unresolved - the utility has returned to full compliance and continues to serve approximately 20,100 residents under all current EPA drinking water standards.
Data: EPA SDWIS
Service Area Map
Coverage area for King County Water District No 90 Source: EPA SDWIS service area boundaries.
Service area boundary - Grade A
Service Area Demographics
The King County Water District No 90 serves a community with a median household income of $144,733 and an estimated 190,592 residents across its service area. Approximately 49% 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.
Superfund Proximity Note: This service area ranks in the 70th percentile nationally for proximity to Superfund (NPL) sites.
Infrastructure Risk
Detected Contaminants
How King County Water District No 90 compares to EPA limits
What This Means For You
Surface Water Treatment Rule at 2 mg/L exceeds the EPA maximum of mg/L.
PFAS Detected in Service Area
PFAS ("forever chemicals") have been detected in water serving this system's area. 9 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 5 ZIP codes across 4 communities.
ZIP-Area Home Safety Context: A (99/100)
This is the average Home Safety Score for 1 of 5 service-area ZIP codes with all required score domains observed. It is not a grade for the water utility.
Model 4.0.0 uses SDWIS identity plus accepted ECHO SDWA lifecycle-based water compliance, the UCMR 5 PFAS MCL screen, EPA radon zone, and annual EPA AirData AQI across three equally weighted domains. Missing required evidence suppresses the score.
Violation History
Status breakdown for accepted records with record years 2021-2026: 2 resolved, 0 archived, 0 addressed, and 0 unaddressed. Under this source contract, current noncompliance is the sum of addressed and unaddressed records. Archived and resolved records are excluded from current noncompliance.
Recent Violations
| Date | Contaminant | Type | Status |
|---|---|---|---|
| July 1, 2024 | Surface Water Treatment Rule | Non-health-based | Resolved |
| July 1, 2021 | Surface Water Treatment Rule | Non-health-based | Resolved |
Contaminants Detected
The following contaminants have been flagged in EPA records for this water system:
| Contaminant | Category | Violations | Health-Based |
|---|---|---|---|
| Surface Water Treatment Rule | Treatment Failure | 2 | No |
Lead & Copper
EPA Lead and Copper Rule evidence attributed directly to this water system:
| Lead Level | Exceeds Action Level | Sample Date |
|---|---|---|
| 0.0012 mg/L | No | N/A |
No copper action-level exceedance record appears for this PWSID in the accepted LCR snapshot. This does not establish a clean copper measurement.
Radon Risk in Service Area
Dominant radon zone for ZIP codes served by this system: Zone 3 (Low Risk)
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: Service area ZIP codes sourced from EPA Community Water System Service Area Boundaries v3 (March 2026 release). These ZIPs reflect the actual deployment footprint recorded by WA or modeled from parcel and building-footprint data.
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?
The accepted 2026Q2 ECHO snapshot shows no current noncompliance for King County Water District No 90; its 2 accepted 2021-2026 records are resolved or archived. Historical compliance status does not establish conditions at a specific tap.
How many people does King County Water District No 90 serve?
King County Water District No 90 serves approximately 20,100 people across 5 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 →
Frequently Asked Questions
How to cite this page
ZipCheckup. (n.d.). King County Water District No 90 (WA): 2 EPA Violations. https://zipcheckup.com/water-system/wa5341150/
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title = {{King County Water District No 90 (WA): 2 EPA Violations}},
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url = {https://zipcheckup.com/water-system/wa5341150/}
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What You Can Do
Test your water
Home test kits can detect lead, bacteria, and other contaminants at your tap. Find the right filter →
Check your specific ZIP code
Water quality can vary within a system. View nearest ZIP report →
Contact your utility
King County Water District No 90 (EPA ID: WA5341150) - request the latest Consumer Confidence Report or ask about specific contaminants.