without a deposit or other adequate assurance of performance from the customer, to the extent that the extension of service results in a positive contribution to the utility's overall cost of service over a twenty (20) year period. For the purposes of this subsection, a water or wastewater utility's extension of service to a developed but underserved area will be considered as resulting in a positive contribution to the utility's overall cost of service over a twenty (20) year period to the extent that rates to be paid by fifty percent (50%) or more of the customers who could be served by the extension of service would enable the utility to fully recover the weighted cost of debt and depreciation expense attributable to the cost of the main extension for the extension of service.
IC 8-1-2-46.2