Experimental investigation on water saving by the reuse of washbasin grey water for toilet flushing

The paper presents the results of an experimental investigation aimed at estimating the water saving obtained by reusing washbasin grey waters for toilet flushing in domestic bathrooms. Six Italian households characterised by different number of users largely heterogeneous in age, gender, occupation and customs were selected for the experimental campaign. Washbasin and toilet uses for each selected household were monitored recording chronological series of time instants of washbasin tap opening/closure and of toilet flushing operations. On the basis of water balances on a short time scale, acquired data enabled the evaluation of water saving and unused grey water deriving by the adoption of a simple grey water reuse scheme. Specific dimensionless variables were adopted to present the results and to enable their use within the ranges of practical applications.