Component Analysis

Bursts and Background Estimates of Real Losses

Identifying Key Influences on different types of Water Leaks

This internationally applicable overview concept was first developed in 1992-94 by Allan Lambert for the UK National Leakage Control Initiative, for calculating components of Real Losses based on the various key parameters which influence them. The original paper (1994A) and a follow-up paper (1996A) are available for downloading from the Free Papers & PPTs page of this website. The concept was applied in several of the ‘Managing Leakage’ Reports of the UK National Leakage Initiative in 1994.

Components of Real Losses on different parts of the infrastructure (mains, service connections etc.) are considered to consist of Background leakage at joints and fittings, Unreported leaks, and Reported leaks; each have different characteristic frequencies, flow rates and duration.

Bursts and background Estimates of Real Losses (BABE)

Acknowledgement: Jairo Tardelli Filho (SABESP, Brazil)

When calculating components of Annual Real Losses volume, undetectable small background leaks are assumed to run continuously.

For detectable reported and unreported leaks, typical burst flow rates for mains, and for services, are specified at a standard pressure of 50 metres, then adjusted to actual pressure using appropriate assumptions for FAVAD N1 values.

Utility policies and standards of service for average run-times of reported and unreported leaks are simulated by splitting run time into three time elements – Awareness, Location and Repair time. The individual components of Real Losses can then be calculated from first principles and (with some minor adjustment of assumptions for background leakage) matched to the Real Losses calculated from an annual water balance, as shown in the Table below. This is similar to the process of calibrating a distribution system network analysis model by adjusting the roughness values for mains until a match is obtained with field data.

Real Losses calculated from an annual water balance Bursts and background Estimates of Real Losses (BABE)

Once the component analysis model has been calibrated, ‘what-if’ predictions can be made to predict the effect of changing pressures, repair times, active leakage control methods etc.

The component analysis concept can also be used for calculations of Economic Leakage levels (with or without pressure management), and analysis of night flows.