Radon levels in Waukesha, Wisconsin
LowEPA Zone 1Predicted long-term basement average of 1.4 pCi/L (model estimate) across the 4 modeled ZIP codes in Waukesha - about 24% below the US average of 1.8, about 32% below the Wisconsin average of 2.0. Ranked #12 of 15 Wisconsin cities on this site. Most of the city lies in Waukesha County.
Test Waukesha, WI once anyway - radon varies house to house
The predicted basement average here is 1.4 pCi/L, below the EPA's 2 pCi/L "consider fixing" threshold. That's good news for the area - but the EPA still recommends every home be tested, because foundation cracks, soil pockets and ventilation make one house very different from its neighbor. One inexpensive kit settles it.
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Predicted (model estimate). The pCi/L figures on this page are long-term area averages from a peer-reviewed national model built on millions of real radon tests (2001-2021). They describe the typical home in this area - not your home, which can be several times higher or lower. The EPA radon zone is a separate, 1993 county-level classification. Measured state test results are shown separately below, labeled with their source and years. How the numbers work.
1.4 ± 0.10
pCi/L predicted basement mean (model SD)
1.4 ± 0.07
pCi/L predicted upstairs (above-ground) mean
1.2-1.6
range of ZIP-level basement predictions in the city
0%
of Waukesha ZIPs predicted ≥ 4 pCi/L (0% ≥ 2)
Measured radon tests in Waukesha County (Wisconsin Department of Health Services, 1995-2016)
Actual results from home radon tests reported to the state, separate from the model estimate above. Coverage: 1995-2016.
- Measured mean
- 7.5 pCi/L
- Results ≥ 4 pCi/L
- 62%
- Results ≥ 2 pCi/L
- 80.8%
- Sample
- 8,577 tests
| Figure | Model (predicted) | State tests (measured) |
|---|---|---|
| Mean, pCi/L | 1.6 basement | 7.5 |
| Share ≥ 4 pCi/L | not a model output | 62% |
The measured mean runs 5.9 pCi/L above the model because state test data is voluntary and skews toward basements, winter, and homeowners who already suspected a problem, while the model estimates the long-term average across all homes.
Source: Wisconsin Indoor Radon Test Results (Wisconsin Radon Map Service, layer 3), Wisconsin Department of Health Services. No license statement on the public feature service. Method and download.
What this means for Waukesha
The typical Waukesha home is predicted below 2 pCi/L, the lowest band. That describes the average house; the ZIP-level predictions inside the city still span 1.2 to 1.6 pCi/L.
The city figure is not a separate estimate: it is the mean of the model's ZIP-code predictions, weighted by the share of the city's land in each ZIP (Census 2020 ZCTA-to-place relationship file). Note that the EPA classifies Waukesha County as Zone 1 while the newer model predicts 1.4 pCi/L for Waukesha; where they disagree, we grade on the model but show both.
Comparable Wisconsin cities: Wauwatosa (1.4), Milwaukee (1.2), West Allis (1.2), Sheboygan (1.2).
ZIP codes in Waukesha
ZIPs that overlap the city, largest share of its land first. Predicted basement and upstairs means are model estimates; ZIPs the model does not cover show a dash.
| ZIP | Share of city | Basement | Upstairs | Grade |
|---|---|---|---|---|
| 53188 | 45% | 1.3 ± 0.09 | 1.3 | Low |
| 53186 | 27% | 1.2 ± 0.09 | 1.2 | Low |
| 53189 | 24% | 1.6 ± 0.11 | 1.6 | Low |
| 53072 | 5% | 1.3 ± 0.09 | 1.4 | Low |
Testing help in Wisconsin
Wisconsin's radon program page is at www.dhs.wisconsin.gov; it lists testing and certified-mitigator guidance. EPA state radon contacts page. If a test comes back at 4 pCi/L or higher, mitigation typically costs $800-$2,500 installed; use EPA find-a-professional and read the mitigation guide.
Waukesha radon questions
- Is radon high in Waukesha, Wisconsin?
- Low. Averaging the model's ZIP-code predictions across Waukesha (weighted by how much of the city each ZIP covers) gives a long-term basement mean of 1.4 pCi/L - about 24% below the US average of 1.8 and about 32% below the Wisconsin average of 2.0. That is below the EPA's 2 pCi/L "consider fixing" threshold, though individual homes still vary. Waukesha ranks 12 of 15 Wisconsin cities on this site.
- What do actual radon tests show around Waukesha?
- Wisconsin Department of Health Services publishes results for Waukesha County (not the city alone) covering 1995-2016 (8,577 tests): an average of 7.5 pCi/L, 62% of results at or above the 4 pCi/L action level. These are voluntary home tests, so they skew toward basements and toward homes where radon was suspected; the model's predicted basement average for Waukesha is 1.4 pCi/L.
- Which Waukesha ZIP codes have the highest radon?
- Predictions for the 4 modeled ZIP codes in Waukesha range from 1.2 to 1.6 pCi/L in the basement. 0% of them are predicted at or above 4 pCi/L and 0% at or above 2. The city is fairly uniform, so the city-wide number is a reasonable guide for any neighborhood.
- Should I test for radon in Waukesha?
- Yes, once. The EPA recommends testing every home regardless of area. A short-term kit costs little and settles the question for your house; Waukesha's low predicted average describes the typical home, not yours.
- What does EPA Radon Zone 1 mean for Waukesha?
- Waukesha sits mainly in Waukesha County, which the EPA classifies as Zone 1 - highest potential (predicted average > 4 pCi/L). The zone map dates from 1993 and covers whole counties. The newer model's city average of 1.4 pCi/L does not line up with Zone 1, which is common - the EPA itself says high-radon homes exist in every zone. Neither replaces a test of your own home.
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