The influence of water conservation on drain sizing for building drainage systems

Water conservation is a prerequisite to a sustainable built environment. The effect of reductions in water throughflow on the operation of building drainage systems must be understood and incorporated into the design of building drainage networks. The water consumption represented by water closet (w.c.) usage identifies w.c. flushing as the major contributor of waste water from domestic and commercial buildings and hence the water closet becomes the defining appliance in terms of identifying appropriate drain sizing techniques. Within the building envelope w.c. discharge flow is subject to wave attenuation which has a predominant role to play in the final solid transport distance expected following w.c. operation. This paper discusses the interaction of the parameters governing solid transport and illustrates the application of mathematical modelling techniques to predict transport distance under water conservation criteria.