What is an indirect waste pipe?

An indirect waste pipe is defined as a waste pipe that discharges into the drainage system through an air gap. This design is crucial for preventing contamination of the potable water supply. By utilizing an air gap, any potential backflow or siphonage that could introduce waste materials back into the clean water system is effectively mitigated.

This method is commonly employed in scenarios where water may not come from a sanitary source, such as in kitchen sinks or laundry tubs. The air gap serves as a physical barrier, ensuring that any discharged waste remains separate from the drinking water supply, thereby promoting public health and safety.

The other choices do not accurately describe the function of an indirect waste pipe. A direct connection to the drainage system would not provide the necessary separation to avoid contamination. A pipe designed to carry rainwater relates to storm drainage, which does not involve waste management. Coated waste pipes may pertain to different insulation needs but do not define the concept of indirect waste disposal. Therefore, the focus on the air gap in option B makes it the correct understanding of an indirect waste pipe.