Oklahoma septic rules, in plain English
Home septic systems in Oklahoma are regulated by the Department of Environmental Quality under OAC Title 252, Chapter 641 (DEQ rules, OAC 252:641). Cities can add their own rules.
Before building
- A soil test or certified soil profile decides which system the lot can use (Oklahoma DEQ sewage treatment page).
- Minimum lot sizes apply, and systems must meet separation distances from wells, property lines and water (DEQ rules, OAC 252:641, 252:641-1-3).
- Average daily flow is figured at 200 gallons/day for up to 2 bedrooms plus 66 gallons/day per added bedroom (252:641-1-3).
Inspection before backfill
All new installations, modifications and repairs must be inspected and approved by DEQ, or installed and self-inspected by a DEQ-certified installer, before backfill or use. The installer requests any DEQ inspection. Certified installers submit the final report (Form 641-576) within 15 days (Oklahoma DEQ sewage treatment page).
Certified installers
DEQ publishes a DEQ list of active certified installers. Hiring a certified installer avoids waiting on a DEQ inspector.
Selling a home
No state septic inspection is required at sale (OSU Extension: Basic Septic System Rules for Oklahoma). Many buyers order one anyway.
Problems or complaints
DEQ's environmental complaints line is 1-800-522-0206 (DEQ aerobic systems fact sheet).