Page 74 - Water Loss Control

56 Cha pte r F i v e

both the real losses and the apparent losses in order to see if there is room for economi-
cally justifiable real and/or apparent loss reductions.
Models to determine the long-term economic optimum volume of water loss, like
used in England and Wales, for example, can be highly complex and very labour- and
data-intensive.
However, by using a short-term economic analysis, which is basically transferring
water loss volumes into values and comparing them to the cost of intervention, a much
less labour and data intensive approach exists to provide a utility with the economic
water loss benchmarks it needs to determine its optimum intervention program. Each
water system will have different types and degrees of loss and each has a potential solu-
tion and each solution has a cost. However, before the cost to benefit ratio can be defined
the potential solutions have to be identified and graded technically. In addition to hav-
ing a good return or cost to benefit, it is also important when considering intervention
to take into account the local conditions and the sustainability of the method or solution
adopted. Water losses don’t go away they keep on coming back. Water loss control is
not a one-time exercise it is a continuous and changing solution to an ever-changing
problem.
See Chap. 9 for a detailed discussion on determining the economic optimum
volume of water loss.

5.4 Design the Right Intervention Program
As we already know from previous chapters there are two basic forms of water losses—
real and apparent losses—and for both types of losses the right intervention program
needs to be designed. The design of the right intervention program is directly con-
nected or interlinked with the process of determining the economic optimum volume
of water losses.
This section will provide a brief overview of the common intervention methods
available against real and apparent losses which form the bases for the design of every
water loss control program. Chapters 11 to 15 will provide an in-depth discussion of all
intervention methods available against apparent losses and Chaps. 16 to 19 will provide
an in-depth discussion of all intervention methods available against real losses.

5.4.1 Real Loss Intervention Methods
The decision on which intervention methods are appropriate for the given situation will
depend very much on which factors are attributing to the real losses in any particular
system and the cost benefit of each intervention method. Figure 5.3 shows a component
break down of intervention methods against real losses. Each of the four arrows repre-
sents an intervention method or a set of intervention methods against real losses.
Depending on the local situation the final real loss intervention program may consist
only of one or a combination of several or all intervention methods which will serve to
bring the real losses down to the economic optimum volume.

5.4.2 Apparent Loss Intervention Methods
Just as for the real losses there is also a set of intervention methods available to reduce
the volume of apparent losses down to the economic optimum point. Figure 5.4 shows
a component breakdown of intervention methods against apparent losses. Each of the
four arrows represents an intervention method or a set of intervention methods against