Terms of the Trade: What Is a DWV System?

We may not like to think about it much, but there's a lot of work that goes into removing waste and gray water from buildings. In modern structures, what makes it all possible are drain-waste-vent systems, also known as DWV systems. Regulated neutral air pressure in drains from sinks, toilets, and showers or tubs facilitates free air flow. A downward slope in the plumbing keeps everything moving away from the building, with traps that prevent gases from entering where they shouldn't. In residential structures, the systems are vented through the roof.