Texas Water Code - WATER § 60.341. Rates, Tolls, and Charges

(a) Where bonds are payable wholly from revenues, the governing body shall fix and from time to time revise the rates, tolls, and charges from the sales and services rendered by the district, the revenues from which are pledged, to the end that the rates, tolls, and charges will yield sufficient money:

(b) Where the bonds are payable both from taxes and from revenues, the governing body shall fix and from time to time revise the rates, tolls, and charges for sales and services rendered by the district, to the extent pledged, which will be sufficient to assure compliance with the resolution authorizing the bonds or the trust indenture securing them.