Official sources checked August 29, 2026
Collin County, Texas septic permits and requirements
Permitting authority
Collin County Engineering — Development Services / OSSF Program
Development Services: [email protected]. Applications are handled through the county Citizen Self Service portal when Collin County is the authorized agent.
Confirm the permitting authority
For property outside city limits, Collin County requires an OSSF permit through its Citizen Self Service portal. Inside city limits, responsibility can vary; the county directs applicants to the TCEQ authorized-agent list and states that Collin County is the authorized agent when the city is not separately listed.
New construction workflow
When a new structure will connect to a new OSSF, the county instructs applicants to apply for the development permit first. Staff then sends the associated OSSF permit through the portal rather than having the applicant create a separate duplicate development/OSSF workflow.
Licensed design professional
Collin County directs owners to a currently licensed Registered Sanitarian or Professional Engineer for new OSSF designs and repair designs. The county maintains a courtesy list but does not require use of a particular provider.
Existing septic and property improvements
When Collin County is the permitting authority, adding a structure, altering a structure, or building a swimming pool on property with an existing OSSF requires a review-of-existing-OSSF permit through the county portal.
Current published OSSF fees
The county fee schedule lists residential OSSF fees of $310 without a maintenance requirement and $335 with maintenance; commercial fees of $450/$475; existing-septic review at $50; and repair/upgrade fees of $100 for less than 100 feet of line or $150 for more than 100 feet. The county notes that work affecting 50% of the system is permitted as a new OSSF. Confirm the current fee schedule before filing.
Inspection and re-review
Collin County publishes an OSSF inspection handout and charges additional reinspection/re-review fees in specified circumstances. Applicants should keep the system accessible until required county inspections are complete.
Official sources
- Collin County — On Site Sewage Facilities
- Collin County — Development Services FAQ
- Collin County — Development Services and Fees
SepticScope summarizes public-agency information for planning purposes. The permitting agency's current instructions control if they differ from this guide.