If at any time the rates and charges fixed in this subchapter shall not be sufficient to pay the costs of operation and maintenance of the water system, to provide an adequate depreciation fund, and to pay the principal of any and all interest upon all water revenue bonds issued by the city which may be then outstanding, the City Council shall forthwith increase the rates fixed by this subchapter so that the same shall be sufficient to provide adequate revenues for these purposes.
(1983 Code, § 21-169)