Rockwall County, TX: EPA's radon zone, explained

Rockwall County is mapped as Zone 3 - Low Potential by EPA — meaning the county-wide average indoor level is predicted below 2 pCi/L. Nationally, Rockwall County ranks higher in radon potential than 27% of rated counties (the 27th percentile).

How Rockwall County compares

Rockwall County, Texas is home to about 137,044 people across 127.229 square miles. That works out to roughly 1,077 people per square mile. By population, Rockwall County is the 178th largest of every county sharing its EPA zone — the 83rd percentile by population within that zone. EPA's geology-based Region 6 groups Rockwall County with 502 other counties nationally sharing its underlying rock and soil profile.

Zone vs. an actual test

At Zone 3, Rockwall County's predicted county average is under the national indoor average (~1.3 pCi/L) and well below EPA's 4 pCi/L action level — outdoor air nationally runs about 0.4 pCi/L for comparison. A Zone 3 rating means Rockwall County's county-wide average is predicted low, but EPA is explicit that a meaningful share of homes in low-potential zones still test above the action level — a low zone is not a reason to skip testing.

Testing and mitigation in Rockwall County

For a Rockwall County homeowner, the order is simple: test first, since a kit costs a small fraction of what mitigation would. Only if the result clears 4 pCi/L does a system — typically $800–$2,500, about $1,200 for a common install — become worth pricing out.

Find Texas's state radon program

For Rockwall County, an ongoing number beats a one-time test - a Airthings radon monitor tracks Rockwall County's levels over time. RadonZoneCheck earns a commission there, at no extra cost to you. Use code RADONZONE-10OFF at checkout for 10% off.

Where Rockwall County's figures come from

The methodology guide shows exactly which EPA and Census sources feed Rockwall County's numbers. Whatever zone Rockwall County carries, the zone explainer covers what it does and doesn't tell you about any one house.