9.1 INTRODUCTION

As discussed in Chap. 2, water losses come in two basic forms:

• Real losses (sometimes referred to as physical losses)

• Apparent losses (sometimes referred to as nonphysical losses)

In addition to reducing water loss during an optimization project, water system operators often look to reduce energy losses caused by inefficient pumping. Pump scheduling and pump efficiency programs often form part of a water loss control or system optimization project. More information on the various methodologies for reducing pumping-related energy costs can be found in Chap. 18, Article Four. This chapter will briefly review some of the most common methods of reducing losses and leads into in-depth discussions in Chaps. 10 14.

Lambert and Herner1 published one of the most recent definitions of real and apparent losses in the IWA Blue Pages, as follows:

Real losses are physical water losses from the pressurized system, up to the point of customer metering. The volume lost through all types of leaks, bursts [often referred to as breaks], and overflows depends on frequencies, [system pressures,] flow rates, and average durations of individual leaks.

Apparent losses consist of unauthorized consumption (theft or illegal use), and all types of inaccuracies associated with production metering and customer metering. Underregistration of production meters, and overregistration of customer meters, leads to underestimation of real losses. Overregistration of production meters, and underregistration of customer meters, leads to overestimation of real losses.

Each water system will have different types and degrees of loss, and each...