Sec. 1. (a) Except as provided in subsection (b), the governing body may determine and impose rates and charges of the district based on the following:
(1) A flat charge for each system.
(2) Variable charges based on the capacity of a system.
(3) Other factors that the governing body determines are necessary to establish just and equitable rates and charges.
(b) In:
(1) a county having a population of more than four hundred thousand (400,000) and less than seven hundred thousand (700,000); and
(2) a county having a population of more than two hundred fifty thousand (250,000) and less than three hundred thousand (300,000);
rates and charges may be imposed or changed under this chapter only after approval by the county legislative body.