Water saving potential of domestic water reuse systems using greywater andrainwater in combination

For a sustainable urban future, society must move towards the goal of effic ient and appropriate water use. Reuse of domestic greywater and rainwater h as a significant role to play in this task. In this study, rainfall time se ries have been used in conjunction with estimates of domestic water applian ce usage generated by the Monte-Carlo simulation technique to predict long term system performance. Model results show that changes in the attributes of household occupancy, roof area, appliance type and storage volume affect the water saving efficiency of a single store reuse system. Considering gr eywater and rainwater in combination, the greatest rate of increase of effi ciency with storage size occurs in the range 0-100 litres. Further analysis of small volume storage and reuse indicates that savings of up to 80% of t he WC flush water can be made with less than 50 litres storage. However, th e collection of rainwater in addition to greywater in a single store reuse system offers little improvement in water saving efficiency. Small volume d omestic water reuse systems lend themselves to application in the urban hou sing environment and therefore offer potential in the move towards a more s ustainable city. (C) 1999 IAWQ Published by Elsevier Science Ltd. All right s reserved.