Short-term kit
RA100 short-term liquid scintillation radon test kit
- Lab fee extra
Method: Liquid scintillation
In home: 48 to 96 hours
Locations and reports
Radon Levels in Hays County, Texas
EPA puts Hays County in Zone 3, its lowest radon zone, and only 23 radon tests from it are on file with CDC (2008 to 2017, laboratory totals). Homes with elevated levels occur in all three zones, so only a test measures yours.
Data checked By Radon411Methodology
Highest bordering
9.3%
Travis County
- Travis
- 9.3%
1 of 5 neighbours have 30+ tests, 2007 to 2016
Nearest county
9.3%
Travis County, 24 miles
- Travis
- 9.3%
- Texas
- 10.4%
Share at 4+ pCi/L, 408 tests, 2007 to 2016
Ground above low
5.4%
21.9 pts below Texas
- Hays
- 5.4%
- Texas
- 27.3%
Share of land USGS rates moderate or high potential
Tests reported
27
Too few for a share
- Hays
- 27
- Needed
- 30
2007 to 2016, laboratory
EPA radon zone
Zone 3
Lower potential
- 1
- 2
- Zone 3
1 highest, 3 lowest
EPA predicts under 2 pCi/L indoors
Read a result for Hays County
Starts at EPA's action level
EPA’s own thresholds; the figures are the area’s, never this home’s.
EPA’s reading of 4.0 pCi/L
At or above 4 pCi/L
- Under 20 to 1.9 pCi/L
- 2 to 4consider a fix
- 4 and aboveEPA says fix it
This result is at or above 4 pCi/L. EPA recommends fixing a home when the radon level is 4 pCi/L or higher.
The data
Hays County, At a glance
Hays County at a glance
Predicted: EPA radon zone
EPA Zone 3: lower predicted potential
USGS geologic potential: Low across 95% of the county's area
Predicted: EPA Map of Radon Zones
Measured: tests reported to CDC
Radon tests reported for Hays County, 2008 to 2017, laboratory
CDC holds 23 reported tests for Hays County over the 2008 to 2017 laboratory totals, with a median of 0.5 pCi/L: too few to describe a county (Radon411 reads a share from 30 tests up). Hays County beside the counties around it is how this page reads it.
What these figures count
Only 23 tests were reported to CDC for Hays County over 2008 to 2017 (laboratory totals), and tests are often run on homes being sold or already suspected of a problem: so few describe neither the county nor this house.
Measured: CDC tracking data. Figure above: 2008 to 2017, laboratory. Measured data period: 2005 to 2017 (every CDC figure on file).
Hays County, Compared
Hays County radon figures, compared
Calculated by Radon411CDC's largest figure for Hays County rests on 27 tests over the 2007 to 2016 laboratory totals, 4 of them at or above 4 pCi/L, so each test moves its share by 3.7 points and no rank or comparison is drawn from it. Results reached as high as 28.1 pCi/L, with a middle value of 0.6 pCi/L.
Travis County, the one bordering county with a figure over the 2007 to 2016 laboratory totals, reported 9.3% of its tests at or above 4 pCi/L. Farther out, Williamson County (48 miles away) at 2.0%, Bexar County (51 miles away) at 6.6% and Bell County (75 miles away) at 14.3% have figures too. Pooled across 140 Texas counties, 10.4% of reported tests reached that level; across every county in the country with a figure, 35.8%.
Statewide for the same period, Randall County reported the highest share (71.4%) and Nueces County the lowest (0.0%). EPA's 1993 map puts Hays County in Zone 3, its lowest label: a predicted county average under 2 pCi/L. USGS geology rates 95% of the county's land low radon potential.
Pooled shares: Radon411's sum of CDC's county counts for one period.
Hays County, Geology
The ground under Hays County
PredictedMost of the ground under Hays County is one class on USGS's geologic map: 94.6% of its land is low radon potential, with 5.4% moderate. The map puts 63.7% of Hays County in the area it calls Southern High Plains and Plateaus and 30.9% in East Texas Province, with one smaller area beside them. USGS gives the first a radon index of 7 and the second 6, both in the low band (5 to 8).
| Area | The rock, in USGS's words | Potential | Radon index | Share of land |
|---|---|---|---|---|
| Southern High Plains and Plateaus | Paleozoic and Mesozoic sandstone, limestone, shale. | Low | 7 | 63.7% |
| East Texas Province | Cretaceous through Quaternary marine sandstone, shale, chalk, limestone, siltstone, clay, and lignite. | Low | 6 | 30.9% |
| Cretaceous Gulfian series | Cretaceous sandstone, shale, limestone, siltstone. | Moderate | 10 | 5.4% |
Names, descriptions and indexes: U.S. Geological Survey, Geologic Radon Potential Map (2025). Shares: Radon411, from the map cut to the boundary.
Hays County beside the ground around it
Across Texas 0.5% of the land is rated high; none of Hays County's is. Of the 5 counties that border it, 2 have more moderate-potential ground, Blanco County the most at 35.3%.
The map rates the ground, not the air in any home.
Local help
Hays County, Local resources
Radon testing and mitigation in Hays County
- Texas Radon GroupTexas Radon Group, run by Texas Tech University, does not license radon professionals and offers free or discounted test kits, and answers questions about testing and mitigation in Texas.Visit the program’s page(opens in a new tab)
- Free and low-cost kitsThe program says:
The Texas Radon Group offers free radon test kits for Texas individuals who qualify.
- Compare kits
- Professionals in Texas7 professionals are listed in Texas.
What Texas's program says
- Licensing of radon professionals
There are no radon certification requirements for the State of Texas at this time, but the National Radon Proficiency Program lists radon testers and mitigators within Texas that have passed a rigorous national certification program.
What it means
Hays County, Questions
Questions about radon in Hays County
Are radon levels high in Hays County?
Over the 2008 to 2017 laboratory totals, 17.4% of the radon tests reported to CDC for Hays County, Texas were at or above 4 pCi/L, and the median reported pre-mitigation result was 0.5 pCi/L. Travis County, the one bordering county with a figure over the 2007 to 2016 laboratory totals, reported 9.3% of its tests at or above 4 pCi/L.
Which counties border Hays County?
Hays County borders 5 counties: Blanco County, Travis County, Comal County, Caldwell County and Guadalupe County.
Products
Hays County, Products
Testing a home in Hays County
No CDC figure names Hays County; the nearest county with one, Travis County (24 miles away), reported 9.3% of its tests at or above 4 pCi/L over the 2007 to 2016 laboratory totals, the only reading nearby until a test of this home. Zone 3 is the lowest label, yet homes at or above 4 pCi/L occur in every zone: a short-term kit (2 to 90 days) is the quick first check in Hays County.
Test kits and monitors3
See every kit and monitor
Long-term kit
RL116 long-term radon test kit
- Lab fee extra
Method: Alpha track
In home: 90 days to 12 months
MonitorAEGTEST
HOUND-3699 radon monitor with a 2.1-inch touchscreen
- C-NRPP 2024/25: Not included
- Battery
- Alarm
- Screen
First reading: Within 1 hour
- See every kit and monitor Test kits and monitors
Test kits and monitors: 1 of 3
Explore
Hays County, Bordering counties
Counties bordering Hays County
Calculated by Radon411- Radon levels in Travis CountyEPA zone 3
9.3%at or above 4 pCi/L
Median 0.8 pCi/L · 408 tests
- Radon levels in Comal CountyEPA zone 3
4.5%at or above 4 pCi/L
Median 0.9 pCi/L · 22 tests
- Radon levels in Blanco CountyEPA zone 3
0.0%at or above 4 pCi/L
Median 0.2 pCi/L · 2 tests
- Radon levels in Caldwell CountyEPA zone 3
0.0%at or above 4 pCi/L
Median 1.1 pCi/L · 2 tests
- Radon levels in Guadalupe CountyEPA zone 3
0.0%at or above 4 pCi/L
Median 0.6 pCi/L · 3 tests
Hays County, Cities and towns
Cities and towns in Hays County
Hays County is growing: the Census Bureau puts it at 304,390 residents on July 1, 2025, up 24.8% from 243,984 in 2020. That works out to 450 people per square mile of land. Austin, the largest place on its list (1,002,632 residents in all), extends beyond Hays County, so no share of the total is worked out for it. Reported testing is thin here: 27 tests over 2007 to 2016, or 0.1 for every 1,000 residents (2025 estimate), where Texas as a whole comes to 0.1.
From Austin to Hays, CDC publishes no figure by town: each reads Hays County's.
| Place | Residents | Since 2020 | Share of residents |
|---|---|---|---|
| Austinextends beyond Hays County | 1,002,632 | +4.2% | Counted whole |
| San Marcosextends beyond Hays County | 77,830 | +14.1% | Counted whole |
| Kyle | 69,917 | +50.6% | 23.0% |
| Buda | 16,166 | +5.7% | 5.3% |
| Dripping Springs | 11,167 | +118.0% | 3.7% |
| Wimberley | 2,909 | +0.7% | 1.0% |
| Uhlandextends beyond Hays County | 1,958 | +23.3% | Counted whole |
| Woodcreek | 1,876 | +4.3% | 0.6% |
| Niederwaldextends beyond Hays County | 1,168 | +73.3% | Counted whole |
| Mountain City | 675 | +6.1% | 0.2% |
| Bear Creek | 476 | +18.7% | 0.2% |
| Creedmoorextends beyond Hays County | 402 | −7.8% | Counted whole |
Places in Hays County with a city page: 1 of 1
- Hays
13 incorporated places, as listed in the U.S. Census Bureau’s 2020 place reference files. “(part)” marks a place that extends into another county. Residents: U.S. Census Bureau population estimates for July 1, 2025 (Vintage 2025). A place that extends beyond Hays County is counted whole, so it has no share.
Hays County, Homes
Homes in Hays County
Of Hays County's 99,775 homes, 65% are detached houses, against 65% across Texas; 21% are in buildings of five or more homes. Much of Hays County is recent building: 64% of its homes have gone up since 2000 and the middle year built is 2005, against 1990 for Texas. 64% of occupied homes are lived in by their owner (Texas: 63%); in the rest a tenant can run a test, but a fix is the landlord's to make.
| Homes | Hays County | Texas |
|---|---|---|
| Housing units | 99,775 | 11,890,808 |
| Detached houses | 65% | 65% |
| In buildings of 5 or more | 21% | 21% |
| Mobile homes | 7% | 7% |
| Built before 1960 | 4% | 13% |
| Built since 2000 | 64% | 37% |
| Middle year built | 2005 | 1990 |
| Owner-occupied | 64% | 63% |
Census Bureau, American Community Survey, 2019 to 2023: estimates from a sample of homes, looser for a small place. Shares by Radon411.