Water Quality Report

Ephraim, WI (54211): High Radon Potential Area

EPA data for Sister Bay Waterworks

High County Radon Potential

EPA records for the water systems mapped to 54211 in Ephraim, WI contain zero recorded violations for inclusive record years 2021 through 2026. This does not establish that every category was monitored or published, and it does not cover events outside that source window.

Data source: U.S. Environmental Protection Agency (EPA) SDWIS

Based on EPA Drinking Water FEMA Flood Data U.S. Census CDC Energy Information Admin. USGS Water Data & 9 more federal sources
Latest air quality, EPA records and weather alerts Current data temporarily unavailable
Current EPA violation data unavailable
Water records and current conditions
Current EPA violation data unavailable
Safety Score N/A
Water Quality No violations
Lead Risk Moderate 0.0061 mg/L, 90th percentile, sample period ending 2023-09-30
NFIP Claim History N/A
Data confidence: High (direct measurement) Medium (sampled / sub-geography) Low (modeled / inferred) Methodology →

At a Glance

  • Water No drinking-water violations in EPA records since 2021.
  • Lead The reported 90th-percentile lead result of 0.0061 mg/L is below the EPA action level, but EPA's health goal for lead is zero; filtration is advisable.
  • Radon EPA Zone 1 - highest county-level potential. This is not a home measurement; test before any threshold comparison.
Contaminant Summary
Evidence unavailable
Report data assembled: Jul 27, 2026 EPA water-system identity: source date or period is not present in ZipCheckup's accepted source record EPA violation history: more than two update cycles old Lead, copper and UCMR measurements: source date or period is not present in ZipCheckup's accepted source record
1
Water System
1,000
People Served
0
Health Violations (since 2021)
Groundwater
Water Source
0.0061 mg/L
Reported Lead Result2.7× the national median for this measure
Zone 1
County Radon Potential · High
$466K
Median Home Value117% above state median ($214K)

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Score Breakdown

Overall Home Safety Score: Score unavailable

Required evidence is missing. Missing values remain unknown and are not imputed or renormalized.

Canonical components

EPA water compliance
100/100
Observed
PFAS MCL screen
Unknown
Evidence missing
EPA radon zone
0/100
Observed
Annual EPA AirData AQI
100/100
Observed

Required domains

Drinking water
Unknown
Indoor environment
0/100
Outdoor environment
100/100

Coverage: 3 of 4 components and 2 of 3 domains observed.

Model 4.0.0; series home-safety-v4-cross-vertical.

Safety & Health (6) HIGH

Your Water System

ZIP code 54211 in Ephraim, Wisconsin is mapped to the water system Sister Bay Waterworks (EPA ID: WI4150510). This system provides water to approximately 1,000 people from groundwater sources.

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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.

5 of the top compounds applied across the surrounding county in USGS pesticide-use estimates appear on EPA drinking-water monitoring lists. See the agricultural pesticide-use section.

📊 EPA Safe Drinking Water · View source →
Environmental Hazards (10) HIGH
Home & Infrastructure (6) HIGH

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Cost & Community (7) HIGH

CPSC product recall notices

These national notices are not matched to this ZIP code or water system.

View all recalls →

📊 CPSC · View source →

Protect Your Home in Ephraim

Based on local data for ZIP 54211, these services may benefit homeowners in your area.

Based on local data for your area. Use the tools below to explore your options.

Gutter Installation & Repair

The median home in 54211 was built around 1953. Aging gutters can cause foundation damage, basement flooding, and mold - a professional assessment can prevent costly repairs.

Typical cost: Gutter installation: typically $1,000–$2,500 for a standard home

Estimate Your Home Maintenance Costs

Window Replacement

The median build year of homes in Ephraim is 1953; check the age and condition of your own windows. ENERGY STAR windows can save $101–$583/year on energy bills.

Typical cost: Window replacement: typically $300–$800 per window installed

Estimate Your Home Maintenance Costs

Roofing Inspection & Repair

Homes built around 1953 may be on their second or third roof. A professional inspection can catch damage before leaks start.

Typical cost: Roof inspection: typically $75–$300; repairs $300–$1,500

Estimate Your Home Insurance Needs

Service recommendations are based on public data for this ZIP code (FEMA, Census ACS, NWS). Actual needs vary by property. By calling, your information will be shared with an independent service provider. ZipCheckup may receive compensation. Cost estimates are approximate and vary by property, condition, and contractor.

Frequently Asked Questions

Is the tap water in 54211 safe to drink?

EPA SDWIS records 0 violations since 2021 across the water systems mapped to ZIP 54211 (primary system: Sister Bay Waterworks), including 0 health-based. The violation table above shows which system each record belongs to. ZipCheckup last updated this page in July 2026. The federal source release date is unavailable, so that month is not presented as source currency.

Where does 54211's water come from?

The recorded water source for Sister Bay Waterworks, a system mapped to ZIP code 54211, is Groundwater. This system serves approximately 1,000 people.

How can I get my water tested in Ephraim?

If Sister Bay Waterworks supplies your home, contact it for its Consumer Confidence Report; otherwise contact the water utility that serves your address, or hire a certified lab for independent home water testing. The EPA recommends annual testing if you use a private well.

Is lead a concern in 54211 tap water?

The Lead and Copper Rule record selected for 54211 reports a 90th-percentile lead result of 0.0061 mg/L for a water system mapped to this ZIP (record date 2023-09-30). The EPA action level is 0.015 mg/L. This result is below the EPA action level; it does not show the lead level in each home.

What is the radon risk for 54211?

54211 is mapped to a county in EPA Radon Zone 1 (high county-level radon potential; EPA recommends testing every home), located in Door County. EPA radon zones range from Zone 1 (highest county-level potential) to Zone 3 (lowest). Testing your home is recommended regardless of zone.

How to cite this page

APA ZipCheckup. (2026). Ephraim, WI (54211): High Radon Potential Area. https://zipcheckup.com/report/54211/
BibTeX 
@misc{zipcheckup-report-54211,
  author = {{ZipCheckup}},
  title  = {{Ephraim, WI (54211): High Radon Potential Area}},
  year   = {2026},
  url    = {https://zipcheckup.com/report/54211/}
}

Page version: October 2026.

Nearby ZIP Code Reports

Water quality comparison for ZIP codes near 54211

ZIP Code City, State Distance Grade Violations
54234 Sister Bay, WI 3.4 mi N/A 0
54212 Fish Creek, WI 3.5 mi N/A 0
54202 Baileys Harbor, WI 7.1 mi N/A 0
54210 Ellison Bay, WI 8.9 mi N/A 0
54209 Egg Harbor, WI 11.6 mi N/A 0
54246 Washington Island, WI 19.9 mi N/A 0
49858 Menominee, MI 22.0 mi N/A 1
49893 Wallace, MI 22.2 mi N/A 0
54235 Sturgeon Bay, WI 24.0 mi D 0
54143 Marinette, WI 24.8 mi N/A 5

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Coverage: 13/17 risk factors Data sources →
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