City, Winnebago County, Illinois
Radon Testing in South Beloit, IL
Updated
Out of 243 IEMA-recorded radon tests taken in South Beloit, 40.7% came back at 4.0 pCi/L or higher, the EPA's action level. Roughly in line with Winnebago County as a whole, at 36.7%. Testing runs $150 to $300 in this area. No number here tells you what your own house will read; only a test does that.
South Beloit is a city in Winnebago County with about 7,946 residents and 3,559 homes, median year built 1991. Neighboring towns include Rockton and Roscoe. It sits directly across the state line from Beloit, Wisconsin.
What IEMA's radon test records show
11.9% of tests in South Beloit came in at 10 pCi/L or higher, well above the action level, and 2.5% were 20 or higher. The highest reading IEMA has on record here is 24 pCi/L. The average result in South Beloit is 4.8 pCi/L, against 4.23 for Winnebago County overall. This comes from IEMA's own records: results licensed measurement professionals submitted between 2003 and July 2019, with only the highest reading kept per address. Not a random sample, and not broken out year by year, but it is the closest primary radon data Illinois makes public.
| Tests | Avg pCi/L | 4+ pCi/L | 10+ | 20+ | |
|---|---|---|---|---|---|
| South Beloit | 243 | 4.8 | 40.7% | 11.9% | 2.5% |
| Winnebago County | 7,642 | 4.23 | 36.7% | 7.9% | 1.1% |
Source: IEMA radon test records, Illinois Emergency Management Agency.
The ground under South Beloit
Underneath Winnebago County, north-central Illinois, sits Ordovician and Silurian dolomite and limestone, the same bedrock family that runs through much of this part of the state, topped by glacial till from the last Ice Age. The EPA's radon zone map puts the county in Zone 1, its top category for predicted indoor levels.
Housing in South Beloit
Census Bureau, American Community Survey 2020 to 2024 5-year estimates.
| Homes (housing units) | 3,559 | 125,002 in Winnebago County |
| Median year built | 1991 | 1971 countywide |
| Built before 1980 | 47% | 74% countywide |
| Attached (rowhome, townhouse) | 4.5% | 4.3% countywide |
| Mobile homes | 7.2% | 1.3% countywide |
| Renter-occupied | 31% | 34.1% countywide |
31.2% of the homes here were built in 2000 or later, one of the higher shares in the county. New construction is not automatically low-radon: a tight, modern house can hold the gas in as well as it holds heat in, and testing after the home is closed up is the only way to know. See our new construction radon testing page. Mobile and manufactured homes make up 7.2% of the housing in South Beloit. Without a basement, testing still happens at the lowest livable level, and any mitigation work looks different than a basement job. 31% of housing in South Beloit is renter-occupied. Illinois does not require landlords to test, but a tenant can ask, and testing between tenants avoids disrupting anyone. See our real estate radon testing page.
What we do in South Beloit
Radon testing, Buying or selling a home, and New construction.
Common questions
Is radon a problem in South Beloit?
Yes. IEMA has 243 radon test results on record for South Beloit, and 40.7% came back at or above the EPA's 4.0 pCi/L action level. Winnebago County as a whole sits in EPA Radon Zone 1, the highest-potential category.
What is the highest radon reading on record near South Beloit?
24 pCi/L is the top reading IEMA has logged for South Beloit, among 243 tests on file. One high neighbor does not predict your own number, which is exactly why testing beats assuming.
Does a new home in South Beloit still need radon testing?
Yes. Radon comes from the ground a house sits on, not the age of the structure, and 31.2% of homes here were built in 2000 or later. A passive vent pipe roughed in during construction helps, but only testing after the home is closed up confirms it's enough.
Need radon testing booked in South Beloit?
Tell us why you're testing and any deadline you're working against. You get a fixed price and a straight answer back.