On-site Sewage Facilities (OSSF)

Septic Systems

When city sewer lines are not available to a residence (300 feet with gravity flow), an On-site Sewage Facility (OSSF), also known as a septic system, maybe an alternative. All OSSFs must be compliant with current State OSSF rules and City Ordinance. The Environmental Health Division processes applications, reviews plans for new OSSFs, reviews plans for modifications of existing OSSFs, and conducts inspections as required. If you have any questions or concerns please call City of San Marcos Environmental Health at 512-393-8444.


Only licensed individuals may do site evaluations, designs or installations on an OSSF. To find a current listing of licensed individuals you may visit the TCEQ website. Look under All License Types and select Group Search Criteria.

  1. Completed Application: Submit an completed application with all required documents.
  2. Submit Payment: Once the application has been received and entered, you will receive notification to submit payment for the plan review and permit. You must submit payment to continue.
  3. Plan Review - Site Suitability Inspection: A designated representative will review your application and plans and notify you of any corrections to be made within 30 days. A field inspection verifying the site suitability may be coordinated with you at the inspector's discretion. 
  4. Issuance of ATC: Once the plan review has been approved, you will be issued an ATC with an expiration date 1 year from date of issue.
  5. Comprehensive System Inspection: Construction may begin at any point during the ATC time period, but you may not ground cover any part of the construction prior to scheduling and passing a system inspection with the City of San Marcos designated representative.
  6. Operational Inspection: Upon passing the system inspection, the inspector will give written permission to cover the site. An operational inspection may be scheduled at the inspector's discretion.
  7. Permit to Operate: Upon passing required inspection(s), the inspector will issue the permit to operate. 


A $415 fee will be assessed for all new installations and repairs to systems requiring updated plans. The cost of a re-inspection is $250. After hours inspections will be charged an additional $250.