Sustainable water systems will meet water service needs at the lowest cost to society and with the lowest environmental impact through maximising water use efficiency first, then maximising water use effectiveness,
optimally matching the quality of demand and supply. Recent regulations and tools can help, and are reviewed against these goals. Building design professionals can help more: they are uniquely positioned to influence
technology and behaviour, the key water use factors. This note was written by the Institute for Sustainable Futures and replaces the original DES 27 Note which was written by Deni Green in June 1999 and reviewed by
David Hood in January 2005.