Official Government Website

Septic Technical Guidance Committee

The Technical Guidance Committee (TGC) is responsible for maintaining the Technical Guidance Manual, reviewing best management practices for individual and subsurface sewage disposal, and providing recommendations on variances and commercially manufactured wastewater treatment components and systems. The TGC comprises six members: one DEQ representative (chair), three health district representatives, one State of Idaho-licensed professional engineer, and one licensed installer. TGC meetings occur quarterly unless, a special issue warrants a special meeting.

The Technical Guidance Manual provides guidance on the design, construction, alteration, repair, operation, and maintenance of standard individual and subsurface sewage systems, their components, and alternatives. The manual is updated periodically to adapt to the dynamic and complex nature of small wastewater disposal systems. Updates are cited below.

Note: This is a large file. If you have difficulty downloading it, try opening it in a different browser or from your hard drive instead of your browser. Right-click on the link, select “Save link as,” navigate to the file on your hard drive, and double-click to open.

Current Updates to the Manual

April 2024

Section 4.23 In-Trench Sand Filter

Section 1.5 Installer’s Registration Permit

Section 4.5 Drip Distribution

Appendix C – Uncommon wastewater flows

January 2024

Section 4.26 Steep Slope System

Section 2.2.3 Effective Soil Depths

Previous Updates to the Manual

September  2023

Section 4.20 RV Dump Station

Section 5.9 Pipe Material for Specified Uses

June 2023

Section Modified or Custom Septic Tank Approvals

Section 1.8 Property Access and Use

Section 3.2.8 Drainfield Excavation Backfilling Materials

Section 3.3 Wastewater Flows

Section 4.3.3 Above-grade Capping Fill System Approval Conditions

March 2023

Section 5.2 Approved Septic Tanks

Section 5.4 Extended Treatment Package Systems

Section 5.13 Proprietary Wastewater Treatment Products

Section 4.3.5 Capping Fill System Construction

This accordion will not appear on the screen

Onsite Wastewater Coordinator

Peter Adams
(208) 954-1438

ver: 3.5.2 | last updated:
Jump back to top of page button