What describes an indirect waste?

An indirect waste is defined as a waste pipe that drains through an air gap to the drainage system. This configuration is important for preventing contamination of the potable water supply. The air gap serves as a protective measure that allows the waste to flow without the risk of back-siphonage or cross-connections, which could potentially introduce waste into clean water.

In a typical plumbing setup, indirect waste systems are often employed in situations where direct drainage could lead to health hazards or where drainage needs to be separated from the supply to prevent any possible contamination.

The other options do not accurately convey the concept of an indirect waste. A waste pipe draining directly into the sewer does not include any protective gap and could pose a risk of contaminating the water supply. A pipe used for emergency drainage may not necessarily involve the mechanisms that define indirect waste flows, and a waste pipe connected to a floor drain may not imply any air gap, thus lacking the safety feature that characterizes indirect wastes.