San Marcos, TX Radon Mitigation and Testing

Q: What EPA Radon Zone is San Marcos in?

San Marcos is in Hays County, EPA Zone 3.

Q: How much does radon mitigation cost in San Marcos?

Radon mitigation typically costs between $800 and $2,000. Most standard systems fall in the $1,000-$1,500 range.

Hays County

EPA Zone 3

Positioned in Hays County between Austin and San Antonio along the Balcones Fault zone, San Marcos sits atop limestone formations and alluvial deposits. Testing data for zip code 78666 is currently unavailable to establish local radon averages. The city's diverse housing stock, from historic downtown buildings to modern suburban developments near Texas State University, may experience varying radon levels due to different foundation types and proximity to geological fault structures.

San Marcos, TX Radon Mitigation

Professional radon mitigation is the most effective way to permanently lower radon levels and protect your household.

San Marcos, TX Radon Testing

Finding qualified radon testing professionals is the first step toward protecting your home.

San Marcos Radon Facts

Key details about the radon risk profile for San Marcos and the 78666 zip code area.

EPA Radon Zone

Zone 3 — Low Risk

County

Hays County, TX

Zip Code

78666

Predicted Screening Level

< 2.0 pCi/L (Zone 3)

San Marcos and the 78666 zip code are located in Hays County, which has an EPA assigned Radon Zone of 3. A radon zone of 3 predicts an average indoor radon screening level less than 2 pCi/L. The EPA recommends testing every home regardless of zone classification.

Radon FAQ for San Marcos, TX

What EPA Radon Zone is San Marcos in?

San Marcos and the 78666 zip code are in Hays County, which has an EPA assigned Radon Zone of 3. A zone of 3 predicts an average indoor radon screening level less than 2 pCi/L.

How much does radon mitigation cost in San Marcos?

Radon mitigation in San Marcos typically costs between $800 and $2,000. Most homes with standard basements can be mitigated with a sub-slab depressurization system in the $1,000–$1,500 range. Factors that can increase cost include complex foundations, crawl spaces, or very high radon levels.

Should I test for radon if I'm buying a home in San Marcos?

Yes. Radon testing should be part of every home purchase. A short-term radon test is typically included as part of the home inspection process and costs $150–$250. If elevated levels are found, you can negotiate mitigation as part of the sale.

Most Active Radon Markets in Texas

Cities with the most user-submitted radon test data in the state.

City	Avg User Radon Level	Submissions
Lubbock	12.67 pCi/L	9
San Antonio	6.57 pCi/L	7
Austin	6.14 pCi/L	7
Dallas	8.00 pCi/L	5
Abilene	4.50 pCi/L	2
Houston	3.50 pCi/L	2
Plano	6.00 pCi/L	1
Frisco	3.00 pCi/L	1
Nacogdoches	No submissions	0