TCEQ provides Information for public water systems and their customers on identifying potential cross connections and preventing contamination from backflow into drinking-water systems.
https://www.tceq.texas.gov/drinkingwater/cross-connection#public
TCEQ Occupational Licensing Section licenses Customer Service Inspectors and maintains a database of licensed Customer Service Inspectors.
https://www2.tceq.texas.gov/lic_dpa/index.cfm