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Penny Green (nee Coombes)

Investigating the feasibility of an integrated closed-loop system for domestic water use

 

The Government’s decision to develop nearly 500,000 houses in this area will have a major impact on the management of the water supply to the East-of-England. Looking at the uses of water in a domestic house, the quantity/quality balance and the concept of cascading water through the system a theoretical ‘water budget’ has been created showing the potential savings.


By integrating the different methods of water management i.e. demand restriction, new sources and the reclamation of water the possibility of a closed-loop system is introduced. A closed-loop system for domestic water use is defined as no net import or export of water across a boundary; however where that boundary lies is critical. For three scales of development: a single house; housing estate and small town a design, based on the concept of ‘local management’ has been completed. This is used to assess what tools could be used to make water savings and also the feasibility of the system in terms of economic, social and environmental impacts.


There are global barriers to the implementation of such systems including: social acceptance; a lack of quality standards for non-potable water and the need to increase the understanding of the real cost of water supply and treatment whilst protecting vulnerable members of society.


From the calculations, the greatest savings, in terms of mains water supply and sewage treatment, are at a town scale with only 18Ml/d required (compared to 118M/d if the Governments target was achieved). However this scheme is based on an integration of the three scales of management, individual houses treating rainwater for potable use, estate/village scale non-potable treatment and reuse, and sewage treatment using anaerobic digestion at the town scale with sustainable urban drainage systems providing storage, conveyance and some treatment.