ABSTRACT
This chapter provides an overview of the elements that make up any piped urban drainage system operating under gravity, including building drainage and other main system components. Even though urban drainage engineers are not normally involved directly in planning, design, and construction of building drainage, it is important that they are at least aware of the main components and layout of systems in and around buildings. This includes, in particular, an understanding of how building drains connect with the main sewer system. Outside building drainage systems have a number of common components, particularly associated with providing access for testing, inspection, and blockage-clearance from the surface. A rodding eye permits rodding along the drain from surface. The main aim of the layout of external building drainage is to minimise the length of pipework and associated components, while ensuring that adequate accessibility is maintained. Ventilation is required in all urban drainage systems, but particularly in foul and combined sewers and storage tanks.
