If any property outside of the territorial limits of the district is placed upon a roll as finally adopted, and at the time such property becomes subject to charge for service and benefit from the district's system, there is an existing outstanding indebtedness owing by the district, the board shall make a separate estimate of the revenue required to be raised to pay or apply upon such indebtedness until it is extinguished, and it shall proceed and certify the same as hereinabove provided, and no dollar rate for raising revenue to extinguish such indebtedness shall be included in the levies made against any properties lying outside of the territorial limits of said district.
When thus levied, the amount of assessment produced thereby shall be added by the general taxing authorities to the general taxes against said lands and collected therewith as a part thereof. If unpaid, any delinquencies in such assessments shall bear interest at the same rate and in the same manner as general taxes and they shall be included in and be made a part of any general tax foreclosure proceedings according to the provisions of law with relation to such foreclosures. As assessment collections are made, the county treasurer shall credit same to the funds of such district.