What characterizes a 'Combination Waste and Vent System'?

A Combination Waste and Vent System is characterized by its capability to handle both waste drainage and venting through the same piping system. This type of system effectively serves multiple fixtures, including sinks and floor drains, allowing waste to be carried away while simultaneously providing ventilation to prevent pressure build-up and siphoning of traps.

The wet venting component comes into play particularly with horizontal runs, which can allow these fixtures to share the same pipe for venting and waste, effectively streamlining installation and reducing the number of pipes needed. This characteristic ultimately enhances the efficiency of plumbing systems, as it balances the need for drainage and the necessary ventilation for proper function.

The other options do not capture the essence of a Combination Waste and Vent System. A system only for waste drainage lacks the essential venting functionality that defines this type. A vertical venting system for toilets does not encompass the combined function of drainage and venting across multiple fixtures, while a separate system for stormwater and sewage ignores the integrated approach that is the hallmark of combination systems. Thus, the emphasis on the system's horizontal wet venting capability for multiple fixtures underlines its distinguishing characteristics.