Western Hills Water District/diablo Gran
EPA ID: CA5010039 · 2,000 people served · 3 ZIP codes
ZipCheckup's reading of EPA records for Western Hills Water District/diablo Gran (CA5010039): no drinking-water violations recorded since 2021. EPA lists no violations for Western Hills Water District/diablo Gran, serving 2,000 people.
Data: EPA SDWIS
Service Area Map
Coverage area for Western Hills Water District/diablo Gran Source: EPA SDWIS service area boundaries.
Service area boundary - average Home Safety grade of mapped ZIPs: A
Demographics of ZIP Codes Served
The ZIP codes associated with Western Hills Water District/diablo Gran have a median household income of $58,333 and about 32,265 residents live in those ZIP codes (Census; not the number of people this system supplies). Approximately 47% of housing stock was built before 1986, which increases the likelihood of lead service lines and older plumbing.
Environmental Justice Note: On average, 54% 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?
Western Hills Water District/diablo Gran'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 80th percentile nationally for proximity to Superfund (NPL) sites.
Infrastructure Risk
Comparable Water Systems
Similar-sized systems in California
System Overview
Western Hills Water District/diablo Gran (EPA ID: CA5010039) is a community water system in California that serves approximately 2,000 people from surface water sources.
This system provides water to 3 ZIP codes across 3 communities.
ZIP-Area Home Safety Context: A (92/100)
This is the average Home Safety Score for 1 of 3 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 |
|---|---|---|
| Below the reporting limit | 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
3 of 3 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 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 Western Hills Water District/diablo Gran (CA5010039) on EPA.gov.
Frequently Asked Questions
Is Western Hills Water District/diablo Gran water safe to drink?
The accepted 2026Q2 ECHO snapshot contains zero violation records for Western Hills Water District/diablo Gran 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 Western Hills Water District/diablo Gran serve?
Western Hills Water District/diablo Gran serves approximately 2,000 people across 3 ZIP codes in California.
Where does Western Hills Water District/diablo Gran get its water?
The primary water source is surface water.
Frequently Asked Questions
How to cite this page
ZipCheckup. (n.d.). Western Hills Water District/diablo Gran Water Report, CA. https://zipcheckup.com/water-system/ca5010039/
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title = {{Western Hills Water District/diablo Gran Water Report, CA}},
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url = {https://zipcheckup.com/water-system/ca5010039/}
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