San Marcos, TX Radon Levels
Check local San Marcos radon levels and find certified testing and mitigation professionals to keep your home safe
San Marcos, TX Radon Facts
EPA Radon Zone
Zone 3 — Low Risk
< 2.0 pCi/L (Zone 3)
County
Hays County, TX
Zip Code
78666
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.
Need Radon Mitigation or Testing in San Marcos?
- 100% Free, No-Obligation Quotes
- Matches You with State-Licensed Hays County Pros
1-800-299-3578
Toll-free · Mon–Fri 8am–6pm ET
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 in Texas with the most user-submitted radon test data, ranked by number of submissions.
| City | Avg User Radon Level | Submissions |
|---|---|---|
| Lubbock | 12.70 pCi/L | 10 |
| 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 |