Accounting for Losses: The Bursts and Background Concept

ABSTRACT Losses of treated water occur through leakage and overflows from the pressurized pipes and fittings in water undertakers’distribution systems and customers’private supply pipes. The UK National Leakage Control Initiative was formed in 1991 to update previous published work on leakage control policy and practice in the UK. Although some published technical relationships exist, there has been no overall methodology which attempts to provide a component‐based estimate of annual losses in different parts of the distribution system for any particular combination of local circumstances, i.e. pressure, burst frequency, burst flow rate, number of properties, length of mains, method of leakage control, standards of service, and waste notice service/enforcement policy. The ‘bursts and background estimate’spreadsheet‐based methodology is designed to provide such estimates. It links ‘night‐flow’and ‘annual losses’concepts, and can be used for a variety of purposes. These include (a) assessment of the likely incidence of losses for different leakage control and waste notice policies, (b) identification (from night flows) of districts in which there are unreported bursts, and (c) assessment of economic target levels for leakage control. The substantial element of annual losses from service pipes, and the considerable influence of pressure on annual losses, are also discussed.