Amendments to Septic Regulations



In an effort to streamline the approval process and eliminate practices within this process that are no longer considered necessary, the Williamson County Board of Health passed the first in a series of revisions to the Williamson County Regulations Governing On-site Sewage Disposal Systems, more commonly known as the Septic Regulations.  These revisions were approved at their September 19, 2023 meeting and include the following updates:

  1. Nonconforming systems and vested rights 
  2. Temporary repairs 
  3. Number of septic systems required for a structure 
  4. Mix of types of systems permitted 
  5. Pump sizing calculations 
  6. Pipe size requirements – APPENDIX 03 APPENDIX 12
  7. Minimum areas and size of septic system areas 
  8. Additional and updated definitions 


            These revisions will become effective October 1, 2023


Additionally, the Board of Health approved the following revision:



            This revision will become effective January 1, 2023


The Board of Health developed a series of “transitional rules” that will allow a given applicant to choose whether they wish to continue their projects under the current regulations or choose to be subject to the provisions of the revisions listed above.  The link below is a hyperlink to the transitional rules. 

On October 17, 2023, the Board of Health approved the following Amendments to the Regulations Governing On-Site Sewage Disposal Systems in Williamson County, with an effective date of November 1, 2023,  related to:


1. Curtain drain requirements associated with Low Pressure Pipe (LPP) systems:

  1. Section 19 – regarding alternative systems
  2. Appendix 5 – regarding soil drainage improvement practices


2. Oversized bathing fixture (tubs) requirements associated with system sizing:

  1. Section 8 – regarding installations on platted parcels
  2. Section 14 – regarding septic tank capacities
  3. Appendix 2 – regarding percolations tests
  4. Appendix 3 – regarding LPP manual
  5. Appendix 6 – regarding permit application process
  6. Appendix 7 – regarding wastewater flow rate calculations
  7. Appendix 9 – regarding conventional system sizing calculations
  8. Appendix 16 – regarding plat notes

The Board also adopted a new Department policy, listed below, regarding limited review of plats and maps; with an effective date of November 1, 2023:

Limited Review Policy-BOH-Oct.17.2023 


Applicants may contact the Sewage Disposal Department, 615-790-5751 and speak to Brenda Bradford, or e-mail her at to determine whether their project would benefit from consideration provided by the revised regulations.  Please provide your name, address of project, and/or your project ID#, so that it can be assessed and next steps determined.  A staff member will be back in touch within two (2) business days.


Check back with this website for future announcements.