(a) The authority shall impose rates and other charges for the sale or use of water or for services sold, provided, or supplied by the authority.
(b) The rates and other charges must be reasonable and nondiscriminatory but sufficient to provide revenue adequate to:
(1) pay the authority's expenses in carrying out the functions for which it is created; and
(2) fulfill the terms of any agreements made with the holders of any of the authority's obligations.