California Water Service Company - Westlake
EPA ID: CA5610016 · 19,533 people served · 5 ZIP codes
ZipCheckup's reading of EPA records for California Water Service Company - Westlake (CA5610016): no drinking-water violations recorded since 2021. From the earliest to the most recent cycle in the EPA data on file, California Water Service Company - Westlake has logged zero violations for the 19,533 people in its service area - a count of records, not a test result for any home.
Data: EPA SDWIS
Service Area Map
Coverage area for California Water Service Company - Westlake Source: EPA SDWIS service area boundaries.
Service area boundary - average Home Safety grade of mapped ZIPs: C
Demographics of ZIP Codes Served
The ZIP codes associated with California Water Service Company - Westlake have a median household income of $160,484 and about 108,980 residents live in those ZIP codes (Census; not the number of people this system supplies). Approximately 66% of housing stock was built before 1986, which increases the likelihood of lead service lines and older plumbing.
Environmental Justice Note: On average, 33% of census tracts in the counties mapped to this service area are designated disadvantaged by the federal Climate and Economic Justice Screening Tool (CEJST, 2022 version). Communities with higher disadvantaged populations often face disproportionate environmental and health burdens, including aging water infrastructure and limited resources for remediation.
🌊 Where Does Your Water Come From?
California Water Service Company - Westlake'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 64th percentile nationally for proximity to Superfund (NPL) sites.
Infrastructure Risk
Comparable Water Systems
Similar-sized systems in California
System Overview
California Water Service Company - Westlake (EPA ID: CA5610016) is a community water system in California that serves approximately 19,533 people from surface water sources.
This system provides water to 5 ZIP codes across 5 communities.
ZIP-Area Home Safety Context: C (66/100)
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
Lead & Copper
EPA Lead and Copper Rule evidence attributed directly to this water system:
| Lead Level | Exceeds Action Level | Sample Date |
|---|---|---|
| 0.003 mg/L | No | 2024-12-31 |
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
3 of 5 ZIP records with known zones are in EPA Radon Zone 1. 2 of 5 ZIP records with known zones are in EPA Radon Zone 2.
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 CA 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 available EPA compliance records for California Water Service Company - Westlake (CA5610016) on EPA.gov.
Frequently Asked Questions
Is California Water Service Company - Westlake water safe to drink?
The accepted 2026Q2 ECHO snapshot contains zero violation records for California Water Service Company - Westlake 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 California Water Service Company - Westlake serve?
California Water Service Company - Westlake serves approximately 19,533 people across 5 ZIP codes in California.
Where does California Water Service Company - Westlake get its water?
The primary water source is surface water.
Federal UCMR5 PFAS Monitoring: No PFAS Reported Above Reporting Levels
This water system was tested under the federal EPA Unregulated Contaminant Monitoring Rule (UCMR5). No PFAS compounds were reported above UCMR5 minimum reporting levels.
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.). California Water Service Company - Westlake Water Report, CA. https://zipcheckup.com/water-system/ca5610016/
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title = {{California Water Service Company - Westlake Water Report, CA}},
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What You Can Do
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California Water Service Company - Westlake (EPA ID: CA5610016) - request the latest Consumer Confidence Report or ask about specific contaminants.