Page 132 - Water Loss Control

114 Cha pte r Ni ne

water used making this more transparent. This in turn may then make demand man-
agement strategies more cost effective. A well-developed strategy for apparent losses
will also reduce wasted expenditure looking for real losses which do not actually exist.
However, it is strictly the supply/demand balance itself that drives the final solu-
tion. In this case, demand is the sum of real losses and consumption. The evaluation has
to be carried out at water resource zone level, that is, where all the customers have the
same level of security of supply taking into account all possible internal and external
drivers. 16
External drivers on water abstracted may include
• Environmental concern over low flows
• Environmental damage from over abstraction
• Environmental drivers, for example, European directives such as the Water
Framework, Birds and Habitats directives, or equivalent
• Carbon footprint of water production

External drivers on water use may include
• Regulatory water efficiency targets 17
• Sustainable water use targets 18

External drivers on the supply/demand balance may include
• Security of supply requirements
• Risk of supply restrictions in drought conditions
• Impact on social and economic progress
• Risk of additional environmental damage in drought conditions
External drivers on leakage performance may include

• Regulatory minimum comparative performance
• Social and economic cost of disruption
• Possible political target
• Carbon footprint of repairs
• Carbon footprint of detection activity

The least-cost solution to meeting the supply-demand balance can be found using a
standard optimisation method, for example, genetic algorithm or unconstrained mixed
integer optimiser, using a formulation such as
Minimise the total cost of operating the system including

• Repairs
• Pressure management
• Proactive leakage detection
• Reactive leakage detection
• Rehabilitation