It shall be the duty of the Director of Finance and the Director of Public Works to recommend, and the duty of the Board of Estimates to:establish rates and charges to make each utility financially self-sustaining at all times; and adjust the rates if the projected profit and loss statement for the current year anticipates a loss and the actual results for the immediate prior year resulted in a loss or deficit. The rates so established shall be at a level sufficient to recover any accumulated loss from prior years. In order to make and assure that each utility is financially self-sustaining, there shall be provision for:operating and maintenance costs; depreciation accruals; amortization of bonds; and reasonable accumulation of surplus. Charges shall be made to various classes of consumers including but not limited to domestic, commercial, industrial, and municipal government and other governmental users of the services of water and sanitary wastewater utilities. City Code, 1976/83, art. 29, §21A(b), (c) Ord. 78-941