Gswc - Willowbrook
EPA ID: CA1910072 · 10,793 people served · 2 ZIP codes
ZipCheckup's reading of EPA records for Gswc - Willowbrook (CA1910072): no drinking-water violations recorded since 2021. Zero violations are listed in EPA monitoring data for Gswc - Willowbrook; a count of records like this is not a water-quality test for the 10,793 residents it serves.
Data: EPA SDWIS
Service Area Map
Coverage area for Gswc - Willowbrook Source: EPA SDWIS service area boundaries.
Service area boundary
Demographics of ZIP Codes Served
The ZIP codes associated with Gswc - Willowbrook have a median household income of $65,154 and about 70,188 residents live in those ZIP codes (Census; not the number of people this system supplies). Approximately 82% of housing stock was built before 1986, which increases the likelihood of lead service lines and older plumbing.
Environmental Justice Note: On average, 49% 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?
Gswc - Willowbrook'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
Comparable Water Systems
Similar-sized systems in California
System Overview
Gswc - Willowbrook (EPA ID: CA1910072) is a community water system in California that serves approximately 10,793 people from surface water sources.
This system provides water to 2 ZIP codes across 2 communities.
Violation History
Lead & Copper
EPA Lead and Copper Rule evidence attributed directly to this water system:
| Lead Level | Exceeds Action Level | Sample Date |
|---|---|---|
| 0 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.
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: Ask your water utility whether running cold water for 2 minutes is enough to flush your plumbing before drinking.
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 Gswc - Willowbrook (CA1910072) on EPA.gov.
Frequently Asked Questions
Is Gswc - Willowbrook water safe to drink?
The accepted 2026Q2 ECHO snapshot contains zero violation records for Gswc - Willowbrook 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 Gswc - Willowbrook serve?
Gswc - Willowbrook serves approximately 10,793 people across 2 ZIP codes in California.
Where does Gswc - Willowbrook 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.). Gswc - Willowbrook, CA: Serves 11K People. https://zipcheckup.com/water-system/ca1910072/
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