Sister Bay Waterworks
EPA ID: WI4150510 · 1,000 people served · 4 ZIP codes
Even though Sister Bay Waterworks accumulated 6 violations over five years, all have been formally resolved — the provider currently meets EPA standards for 1,000 people.
Data: EPA SDWIS Last verified: 2026-04-02
Service Area Map
Coverage area for Sister Bay Waterworks Source: EPA SDWIS service area boundaries.
Service area boundary — Grade C
Service Area Demographics
The Sister Bay Waterworks serves a community with a median household income of $76,329 and an estimated 5,081 residents across its service area. 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 pumped from underground aquifers. 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.
About 1% of homes in Door County, Wisconsin rely on private wells rather than public water systems. Private well owners are responsible for their own water testing and treatment.
Infrastructure Risk
Detected Contaminants
How Sister Bay Waterworks compares to EPA limits
What This Means For You
Consumer Confidence Report Rule at 4 mg/L exceeds the EPA maximum of mg/L.
Contaminant 2040 at 1 mg/L exceeds the EPA maximum of mg/L.
Total Organic Carbon at 1 mg/L exceeds the EPA maximum of mg/L.
Comparable Water Systems
Similar-sized systems in Wisconsin
Estimated Remediation Costs
Average estimated costs across ZIP codes served by this system
Based on national averages for common remediation projects. Actual costs vary by property. Only issues flagged by EPA, FEMA, or state data for each ZIP code are included.
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.
Average Home Safety Score: C (57/100)
Based on water quality violations, lead levels, and radon risk across all ZIP codes served by this system.
Violation History
Recent Violations
| Date | Contaminant | Type | Status |
|---|---|---|---|
| April 1, 2025 | Contaminant 2040 | Monitoring | Resolved |
| September 1, 2024 | Consumer Confidence Report Rule | Monitoring | Resolved |
| January 1, 2024 | Total Organic Carbon | Monitoring | Resolved |
| April 1, 2023 | Consumer Confidence Report Rule | Monitoring | Resolved |
Contaminants Detected
The following contaminants have been flagged in EPA records for this water system:
| Contaminant | Category | Violations | Health-Based |
|---|---|---|---|
| Consumer Confidence Report Rule | Reporting Failure | 4 | No |
| Contaminant 2040 | Other Violation | 1 | No |
| Total Organic Carbon | Disinfection Byproducts | 1 | No |
Lead & Copper
EPA Lead and Copper Rule sampling data for ZIP codes served by this system:
Radon Risk in Service Area
Dominant radon zone for ZIP codes served by this system: Zone 1 (High Risk)
The EPA recommends testing homes in Zone 1 and Zone 2 areas for radon.
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: Let cold water run for 2 minutes before drinking — this helps flush lead from your pipes.
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 the full compliance record for Sister Bay Waterworks (WI4150510) on EPA.gov.
Frequently Asked Questions
Is Sister Bay Waterworks water safe to drink?
Sister Bay Waterworks has only monitoring/reporting violations, which are procedural in nature. The system meets federal health-based standards.
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.
Lead Service Line Inventory
Service line breakdown reported under the federal Lead and Copper Rule Improvements (LCRI) inventory requirement:
This system reports zero confirmed lead service lines in its inventory. Unknown-material counts may still warrant verification.
Federal LCRI rule (effective October 2024) requires every public water system to inventory its service lines and complete lead-line replacement within 10 years.
Source: EPA SDWIS Federal Service Line Inventory (Phase 2) · Submitted 2026
ZipCheckup is not affiliated with the utility or state agency. Inventory figures render verbatim from the public LCRI submission cited above; ZipCheckup does not perform inspections or replacements.
Frequently Asked Questions
What You Can Do
Test your water
Home test kits can detect lead, bacteria, and other contaminants at your tap. Find the right filter →
Check your specific ZIP code
Water quality can vary within a system. View nearest ZIP report →
Contact your utility
Sister Bay Waterworks (EPA ID: WI4150510) — request the latest Consumer Confidence Report or ask about specific contaminants.