Drain-waste-vent system layout, drainage fixture unit-based drain pipe sizing, slope requirements, trap seal function and trap types, and cleanout placement requirements.
Every DWV system carries waste from fixture to sewer through the same gravity-driven hierarchy: fixture drain, horizontal branch, stack, building drain, building sewer. This module works through how drainage fixture units size each level of that hierarchy, why minimum slope requirements exist to keep solids moving rather than settling, how a trap seal physically blocks sewer gas, and where code requires cleanouts so a blockage can be cleared without cutting into the pipe.
By the end of this module you should be able to explain why an S-trap is prohibited under modern codes for a reason rooted in its geometry, not installer preference — a concept Module 9's vent-system content builds on directly.