Water Conservation Optimisation For Building Drainage Systems

Dr. D. P. Campbell

An assessment of the impact of water conserving fixtures and fittings in typical housing development subject to water conservation measures is conducted.  A range of 25 different house styles were simulated with a diversity (random usage) profile based on appliance type and site investigation. The simulation was conducted by DRAINET, a simulation engine based on the Method of Characteristics and a finite difference scheme validated through field studies. Simulation results show that water conservation down to 80% of non-conserved levels did not significantly reduce the solid transport capability of the associated waste water collection system. At 60% of non-conserved levels, there was a marked reduction in the solid transport capability of the waste water collection system. The use of a small (14 litre) intermittent discharge tank (tipping tank) is suggested as a means of extending safe water conservation practices. The tipping tank option would be the best value and fastest technology to implement as a retro-fit option or as a feature in new-builds. Using only approximately 10% of the water conserved, this measure is effective in maintaining solid transport down to 60% of non-conserved levels, which is significantly lower than current water conservation initiatives are achieving.