SECTION 252:641-7-4. Liquid capacity

(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. The liquid capacity for a septic tank used in a small public sewage system shall be 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.

[Source: 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]