What Are the Two Subsystems in Home Plumbing?

The two main subsystems are the water supply system, bringing clean water in, and the drain-waste-vent (DWV) system, safely carrying wastewater out.

The water supply system brings fresh, pressurized clean water into your home. It directly feeds your faucets, toilets, and water heaters.

The drain-waste-vent (DWV) system removes used water using gravity. Crucially, it includes vent pipes that allow air in and block dangerous sewer gases from entering your home.

These systems must never mix. Clean water is protected by supply lines, while waste is handled by the DWV system.

It stands for drain-waste-vent, the system that safely removes waste and vents gases.

Yes. Clean water lines must operate under pressure to properly reach your fixtures.