Current water closet (WC) designs use significantly less water for flushing than previous designs, and this must be considered when determining the drain dimensions, to minimise the possibility of blocking. The flush creates a wave in the drain which attenuates with distance from the WC. This determines the distance solids are carried in the horizontal sections of the drain both within the building and in the connection to the main sewer. Computer software, incorporating an unsteady flow model and including solids transport, has been developed to determine optimum drain diameters and slope. 18 refs.
Primary author(s): McDougall J A;Swaffield J A
Vol.24, No.4, 2003, p.229-243