(a) Water districts formed pursuant to this subchapter shall be operated without profit, but the rates, fees, rent, or other charges for water and other facilities, supplies, equipment, or services furnished by the water district shall be sufficient at all times:
(1) To pay all operating and maintenance expenses necessary or desirable for the prudent conduct of its affairs and the principal of and interest on the obligations issued or assumed by the water district in the performance of the purposes for which it was organized; and
(2) For the creation of adequate reserves.
(b) The revenues of the water district shall be devoted, first, to the payment of operating and maintenance expenses and the principal and interest on outstanding obligations, and thereafter to reserves for improvements, new construction, depreciation, and contingencies as the board may from time to time prescribe.
(c) Revenues not required for the purposes set forth in subsection (b) of this section shall be returned from time to time to the customers of the water district on a pro rata basis, according to the amount of business done with each customer during the period for which the return is made, either in cash, in abatement of current charges for water, or otherwise as the board determines; but such return may be made by way of a general rate reduction to customers if the board so elects.