What is the only way to prevent backflow in drainage and sewage pipes?

Question

Quizplus · Accepted Answer

An air gap is the only way to prevent backflow in drainage and sewage systems. This prevents harmful bacteria from seeping into sinks and other water receptacles in the restaurant. When designing your facility, make sure the contractor and architect are aware of the special requirement of food service establishments.
If you are converting an existing space to fit food safety safety standards, you may also install check valves, which function similarly to air gaps but do not require replacing non-compliant pipes.

What Is the Only Way to Prevent Backflow in Drainage