What is the only TCEQ-approved method for cross-connection control against sewage contamination?

The only TCEQ-approved method for cross-connection control against sewage contamination is an air gap. An air gap provides a physical separation between the outlet of a potable water system and the flood level of the receiving vessel, effectively preventing any backflow of contaminated water. This method is highly effective because it eliminates the possibility of siphoning or back pressure from the contaminated source into the clean water supply.

While other devices like the reduced pressure zone assembly, double check valve, and pressure vacuum breaker serve important roles in backflow prevention, they are typically used in lower-risk situations. An air gap is considered the safest option for protecting drinking water from sewage contamination since it requires no moving parts and cannot fail due to malfunction or wear over time. This is why TCEQ specifically recognizes it as the definitive control method against sewage cross-connections.