Sammamish Plateau Water & Sewer
EPA ID: WA5340900 · 79,362 people served · 7 ZIP codes
ZipCheckup's reading of EPA records for Sammamish Plateau Water & Sewer (WA5340900): a UCMR5 PFAS sample above the level of an EPA PFAS MCL, which takes effect in 2029; this is not a violation. EPA monitoring records reviewed for Sammamish Plateau Water & Sewer list no violations. That describes the federal file only, not a test of the water at any tap, for a utility that reports serving approximately 79,362 people.
Data: EPA SDWIS
Service Area Map
Coverage area for Sammamish Plateau Water & Sewer Source: EPA SDWIS service area boundaries.
Service area boundary - average Home Safety grade of mapped ZIPs: B
Demographics of ZIP Codes Served
The ZIP codes associated with Sammamish Plateau Water & Sewer have a median household income of $171,985 and about 122,249 residents live in those ZIP codes (Census; not the number of people this system supplies).
🌊 Where Does Your Water Come From?
Sammamish Plateau Water & Sewer'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
PFAS in ZIP Codes This System Serves
PFAS ("forever chemicals") have been reported in samples from water systems associated with the ZIP codes in this system's area. These results can come from other water systems serving the same ZIP codes; check the UCMR5 section for any results reported for this system. 24 detections recorded. 8 detections are above the level of a federal PFAS MCL (4 ppt for PFOA and PFOS), with compliance required from 2029.
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
Sammamish Plateau Water & Sewer (EPA ID: WA5340900) is a community water system in Washington that serves approximately 79,362 people from surface water sources.
This system provides water to 7 ZIP codes across 6 communities.
ZIP-Area Home Safety Context: B (83/100)
This is the average Home Safety Score for 3 of 7 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
Lead & Copper
EPA Lead and Copper Rule evidence attributed directly to this water system:
| Lead Level | Exceeds Action Level | Sample Date |
|---|---|---|
| 0.0017 mg/L | No | 2025-12-31 |
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
7 of 7 ZIP records with known zones are in EPA Radon Zone 3.
The EPA recommends testing all homes regardless of radon zone. County radon zones cannot replace an in-home radon test.
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.
- 98014 - Carnation
- 98024 - Fall City
- 98029 - Issaquah
- 98050 - Preston
- 98053 - Redmond
- 98074 - Sammamish
- 98075 - Sammamish
Data Sources
This report uses public data from the EPA Safe Drinking Water Information System (SDWIS). View available EPA compliance records for Sammamish Plateau Water & Sewer (WA5340900) on EPA.gov.
Frequently Asked Questions
Is Sammamish Plateau Water & Sewer water safe to drink?
The accepted 2026Q2 ECHO snapshot contains zero violation records for Sammamish Plateau Water & Sewer in the inclusive 2021-2026 record-year window. This is a compliance-record finding, not a guarantee about water at a specific tap.
How many people does Sammamish Plateau Water & Sewer serve?
Sammamish Plateau Water & Sewer serves approximately 79,362 people across 7 ZIP codes in Washington.
Where does Sammamish Plateau Water & Sewer get its water?
The primary water source is surface water.
Federal UCMR5 PFAS Monitoring: Sample Above an EPA MCL Value or State Standard
This water system was tested under the federal EPA Unregulated Contaminant Monitoring Rule (UCMR5). One or more PFAS measurements were above the level of the EPA MCL for that compound (April 2024 rule, which takes effect in 2029) or above an applicable state drinking-water standard; a monitoring result above that level is not by itself a violation.
EPA's April 2024 PFAS rule sets MCLs of 4 ppt for PFOA and PFOS and 10 ppt for PFHxS, PFNA and HFPO-DA (GenX); water systems must comply from 2029. Other PFAS compounds have no individual federal MCL. A state standard is shown only where this system's state has its own enforceable PFAS limit. Detection results are EPA UCMR5 samples, not a measurement at your tap.
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.). Sammamish Plateau Water and Sewer, WA: Serves 79K People. https://zipcheckup.com/water-system/wa5340900/
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