- (a) Individual on-site sewage treatment system. A septic tank used in an individual on-site sewage treatment system for a residential unit with four (4) or fewer bedrooms shall have a liquid capacity of at least one thousand (1,000) gallons. An additional two hundred and fifty (250) gallons of capacity must be added for each additional bedroom.
- (b) Small public sewage system. Small public sewage systems with a daily flow of one hundred (100) gallons or less may use a septic tank with a liquid capacity of no less than five hundred (500) gallons. Small public systems with daily flows exceeding one hundred (100) gallons shall have a liquid capacity equal to or greater than the average daily flow plus fifty percent (50%), but in no case shall it be less than one thousand (1,000) gallons.
- (c) Two-compartment tanks. The capacity of the influent compartment of a two-compartment tank shall not be less than one-half (1/2) nor more than two-thirds (2/3) of the total required liquid capacity of the tank.
(d) All septic tanks. All septic tanks shall be designed to have:
- (1) a liquid depth of at least three feet (3') but not more than six and one-half feet (6-1/2'); and
- (2) an air space of eight inches (8") or more inside the tank.
Added at 16 Ok Reg 1895, eff 6-11-99
Amended at 19 Ok Reg 1704, eff 6-13-02
Amended at 21 Ok Reg 1618, eff 6-11-04
Amended at 25 Ok Reg 2318, eff 7-11-08
Amended at 41 Ok Reg, Number 23, effective 9-15-24