(a) A county or municipality that applies for or receives funds or financial assistance under § 15.407 of this code or Subchapter K, Chapter 17, of this code must adopt and enforce the model rules developed under § 16.343 of this code to be eligible to participate in this program. The county or municipality by order or ordinance shall adopt and enter the model rules in the minutes of a meeting of its governing body and shall publish notice of that action in a newspaper with general circulation in the county or municipality. A municipality is eligible to participate in this program only if the county in which the project is located adopts and enforces the model rules.
(b) Rules adopted by the commissioners court under this section must apply to all the unincorporated area of the county.

(c) A municipality may adopt rules relating to water supply and sewer services within its corporate boundaries and extraterritorial jurisdiction that are more strict than those prepared under § 16.343 of this code.
(d) A county or municipality that receives funds or financial assistance under § 15.407 of this code or Subchapter K, Chapter 17, of this code may grant an exemption for a subdivision from the requirements of the model rules only if the county or municipality supplies the subdivision with water supply and sewer services that meet the standards of the model rules.