Recent advances in calculating economic intervention frequency for active leakage control, and implications for calculation of economic leakage levels

During the last decade, IWA Water Losses Task Force members have developed a systematic practical approach to the technical management of non-revenue water and its components, with (since 2002) increasing use of 95% confidence limits in these calculations. The current Water Losses Task Force has recently set itself an objective to develop a quick and practical method for calculating economic intervention (for active leakage control to locate unreported leaks and bursts), and short-run economic leakage level. This paper outlines a quick and practical method for assessing economic intervention frequency (and associated budgetary and volumetric parameters) for an active leakage control policy based on regular survey. Calculations are based on three key parameters: natural rate of rise of unreported leakage, marginal cost of water, and cost of intervention. It is hoped this will encourage Utilities that do not currently undertake active leakage control to adopt an ongoing basic active leakage control policy which can be simply demonstrated as being economic for their own situation.