The International Water Association (IWA) strongly advises against the use of NRW as a percentage for target setting. It is still frequently used as a percentage in reporting - especially to non-engineers. It should be understood that the % of NRW is dramatically affected by the annual volume of consumption and so is unreliable for target setting.   There are many references for this, here are some. Who says %s by volume are unreliable?: UK ‘Report 26’, 1980 German DVGW, Note Paper W391, 1986 UK ‘Managing Leakage’, 1994 American WWA Leak Detection & Water Accountability Committee, 1997 OFWAT, UK Economic Regulator, 1997 South African Bureau of Standards, 1999 Malta Water Services Corporation, 1999 New Zealand Water & Waste Association 2001 Water Services Association of Australia 2003 German DVGW, Note Paper 392, 2003 World Bank Institute 2005 Austrian OVGW 2009   I hope this helps. Stuart

Published May 12, 2017 02:30 by Stuart Stapely, NRW Manager at Detection Services