Drain-waste-vent system

All plumbing fixtures are connected, directly or indirectly, to the soil stack  , which is connected at the bottom to the sanitary sewer or septic system and vented at the top. Each fixture    has its own inline trap.

A drain-waste-vent system (or DWV) is the combination of pipes and plumbing fittings that captures sewage and greywater within a structure and routes it toward a water treatment system. It includes venting to the exterior environment to prevent a vacuum from forming and impeding fixtures such as sinks, showers, and toilets from draining freely, and employs water-filled traps to block dangerous sewer gasses from entering a plumbed structure.