Sister Bay Waterworks
EPA ID: WI4150510 · 1,000 people served · 4 ZIP codes
ZipCheckup's reading of EPA records for Sister Bay Waterworks (WI4150510): no drinking-water violations recorded since 2021. Sister Bay Waterworks's compliance file in EPA SDWIS lists no violations, whether health-based or monitoring and reporting, for a utility that supplies water to approximately 1,000 residents.
Data: EPA SDWIS
Service Area Map
Coverage area for Sister Bay Waterworks Source: EPA SDWIS service area boundaries.
Service area boundary
Demographics of ZIP Codes Served
The ZIP codes associated with Sister Bay Waterworks have a median household income of $76,329 and about 5,081 residents live in those ZIP codes (Census; not the number of people this system supplies). Approximately 55% of housing stock was built before 1986, which increases the likelihood of lead service lines and older plumbing.
💧 Where Does Your Water Come From?
Sister Bay Waterworks'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 Wisconsin
System Overview
Sister Bay Waterworks (EPA ID: WI4150510) is a community water system in Wisconsin that serves approximately 1,000 people from groundwater sources.
This system provides water to 4 ZIP codes across 4 communities.
Violation History
Lead & Copper
EPA Lead and Copper Rule evidence attributed directly to this water system:
| Lead Level | Exceeds Action Level | Sample Date |
|---|---|---|
| 0.0061 mg/L | No | 2023-09-30 |
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
4 of 4 ZIP records with known zones are in EPA Radon Zone 1.
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 WI 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 Sister Bay Waterworks (WI4150510) on EPA.gov.
Frequently Asked Questions
Is Sister Bay Waterworks water safe to drink?
The accepted 2026Q2 ECHO snapshot contains zero violation records for Sister Bay Waterworks 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 Sister Bay Waterworks serve?
Sister Bay Waterworks serves approximately 1,000 people across 4 ZIP codes in Wisconsin.
Where does Sister Bay Waterworks get its water?
The primary water source is groundwater.
Frequently Asked Questions
How to cite this page
ZipCheckup. (n.d.). Sister Bay Waterworks Water Quality Report, WI. https://zipcheckup.com/water-system/wi4150510/
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title = {{Sister Bay Waterworks Water Quality Report, WI}},
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url = {https://zipcheckup.com/water-system/wi4150510/}
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