Willowside Mutual Water Company
EPA ID: CA4900561 · 448 people served · 1 ZIP code
ZipCheckup's reading of EPA records for Willowside Mutual Water Company (CA4900561): no drinking-water violations recorded since 2021. Within the EPA records available for it, Willowside Mutual Water Company shows no violations; the system serves about 448 people.
Data: EPA SDWIS
Service Area Map
Coverage area for Willowside Mutual Water Company Source: EPA SDWIS service area boundaries.
Service area boundary
Demographics of ZIP Codes Served
The ZIP codes associated with Willowside Mutual Water Company have a median household income of $93,513 and about 36,842 residents live in those ZIP codes (Census; not the number of people this system supplies). Approximately 67% of housing stock was built before 1986, which increases the likelihood of lead service lines and older plumbing.
💧 Where Does Your Water Come From?
Willowside Mutual Water Company's water is classified in EPA records as a groundwater source. Groundwater is naturally filtered through rock and soil, but it can be vulnerable to PFAS contamination, nitrates from agriculture, and industrial chemicals that seep into the water table.
Infrastructure Risk
Comparable Water Systems
Similar-sized systems in California
System Overview
Willowside Mutual Water Company (EPA ID: CA4900561) is a community water system in California that serves approximately 448 people from groundwater sources.
This system serves ZIP code 95401 in Santa Rosa.
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.
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.
- 95401 - Santa Rosa
Data Sources
This report uses public data from the EPA Safe Drinking Water Information System (SDWIS). View available EPA compliance records for Willowside Mutual Water Company (CA4900561) on EPA.gov.
Frequently Asked Questions
Is Willowside Mutual Water Company water safe to drink?
The accepted 2026Q2 ECHO snapshot contains zero violation records for Willowside Mutual Water Company 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 Willowside Mutual Water Company serve?
Willowside Mutual Water Company serves approximately 448 people across 1 ZIP code in California.
Where does Willowside Mutual Water Company get its water?
The primary water source is groundwater.
Frequently Asked Questions
How to cite this page
ZipCheckup. (n.d.). Willowside Mutual Water Company Water Quality Report, CA. https://zipcheckup.com/water-system/ca4900561/
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