7.1 INTRODUCTION

Good data in means good data out!

Models are an excellent tool to assist the operator with water audits and in water loss management planning, but they should be used with care and diligence. Models are not magic: They are only as good as the concepts they employ, the data that are put into them, and the skill and experience of the user. So care should be taken to ensure that field data captured and coefficients used represent real conditions as closely as may be necessary for a result of required accuracy. If accountable data are not available, estimated data may be used, but the models should include comments columns reflecting the estimated inaccuracy for each component and calculating the final weighted potential inaccuracy. This chapter will discuss some simple examples of such models.

Modeling components of consumption has been part of network analysis models for over 30 years. However, modeling of customer meter accuracy, components of real losses (leakage and overflows), and pressure leakage relationships developed rapidly during the 1990s, to a state of reliability where such models should be considered a standard part of the loss management practitioner s tool kit.

At this stage it should be emphasized that water loss management models are not the same things as network analysis models. Most operators, consultants, and contractors have at some time or another seen or used a network analysis model, which seeks to reproduce the flows and pressures in a distribution network subject to specific inputs...