Onalaska Waterworks
EPA ID: WI6320327 · 18,000 people served · 4 ZIP codes
ZipCheckup's reading of EPA SDWIS for Onalaska Waterworks (WI6320327): no EPA violations recorded in the last five years. Onalaska Waterworks earns a clean bill from EPA monitoring - no violations in five years across a service area of 18,000 people.
Data: EPA SDWIS
Service Area Map
Coverage area for Onalaska Waterworks Source: EPA SDWIS service area boundaries.
Service area boundary - Grade B
Service Area Demographics
The Onalaska Waterworks serves a community with a median household income of $88,206 and an estimated 63,811 residents across its service area. Approximately 52% of housing stock was built before 1986, which increases the likelihood of lead service lines and older plumbing.
💧 Where Does Your Water Come From?
Onalaska 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.
Infrastructure Risk
PFAS Detected in Service Area
PFAS ("forever chemicals") have been detected in water serving this system's area. 10 detections recorded. 2 exceed federal EPA limits (4 ppt for PFOA/PFOS).
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
Onalaska Waterworks (EPA ID: WI6320327) is a community water system in Wisconsin that serves approximately 18,000 people from groundwater sources.
This system provides water to 4 ZIP codes across 4 communities.
ZIP-Area Home Safety Context: B (79/100)
This is the average Home Safety Score for 2 of 4 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 |
|---|---|---|
| 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.
Radon Risk in Service Area
Dominant radon zone for ZIP codes served by this system: Zone 2 (Moderate 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 Onalaska Waterworks (WI6320327) on EPA.gov.
Frequently Asked Questions
Is Onalaska Waterworks water safe to drink?
The accepted 2026Q2 ECHO snapshot contains zero violation records for Onalaska 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 Onalaska Waterworks serve?
Onalaska Waterworks serves approximately 18,000 people across 4 ZIP codes in Wisconsin.
Where does Onalaska Waterworks get its water?
The primary water source is groundwater.
Federal UCMR5 PFAS Monitoring: Detected
This water system was tested under the federal EPA Unregulated Contaminant Monitoring Rule (UCMR5). PFAS compounds were detected below the current state-enforceable MCL.
Current MCL reflects the lowest state-enforceable limit (NYS 10 ppt for PFOA/PFOS, effective August 2020). The federal final MCL of 4 ppt for PFOA/PFOS (EPA April 2024 rule) is not enforceable until April 2029. Detections above 4 ppt but below 10 ppt are below current MCL but above the future federal limit.
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.). Onalaska Waterworks, WI: Serves 18K People. https://zipcheckup.com/water-system/wi6320327/
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url = {https://zipcheckup.com/water-system/wi6320327/}
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