Step 3 · Installing the DWV System

This is the step most people slow down on. Take it one move at a time — there’s no rush, and you can rewind the clip as many times as you need.

This step involves assembling the Drain, Waste, and Vent (DWV) system. Start by laying a bed of gravel in the trench to support the pipes. Using a PVC pipe cutter, cut your Schedule 40 PVC pipes (typically 3-inch for the main line and toilet, 2-inch for sink and shower) to the required lengths. Use a deburring tool to clean the inside and outside of each cut. Dry-fit all pipes and fittings (wyes, elbows, etc.) together, from the main sewer line connection back to each fixture. Use a level to ensure a constant slope of 1/4 inch per foot. Once you have confirmed the fit, disassemble the pieces. Apply purple PVC primer to the outside of the pipe end and the inside of the fitting socket, then immediately apply PVC cement to the same surfaces. Push the pipe firmly into the fitting with a slight twist and hold for 30 seconds. Install the toilet flange so its top will be flush with the finished floor height. Connect the shower drain assembly and its P-trap. Run the vent pipe (typically 1.5-inch or 2-inch) up inside the new wall framing, ensuring it connects to the drain line correctly and terminates by tying into an existing vent or running a new one through the roof, per code.