Which of the following backflow devices is approved in Texas?

The air gap of two times the inlet pipe diameter is recognized as an approved backflow prevention device in Texas. This method involves creating a physical separation between the water supply and the potential source of contamination. The air gap significantly reduces the possibility of backflow, as it effectively eliminates the risk of water traveling back into the potable water system due to changes in pressure.

In contrast, the single check valve, while sometimes used, is not considered adequate by itself in many situations because it does not provide a guaranteed means of preventing backflow in all scenarios, particularly those involving significant backpressure. The standard hose bibb, on the other hand, does not offer any protective features against backflow, making it unsuitable for preventing contamination. Thus, the air gap is a crucial and compliant method for ensuring the safety of drinking water in Texas.