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Contr olling Real Losses in the Field—Pr oactive Leak Detection 287

the test. These boundary loggers will record any change in pressure related to pressure
drops created within the DMA in case the DMA is not hydraulically discrete. In addi-
tion to the boundary loggers, it is also necessary to install loggers inside the DMA. If
any of the pressures recorded by the boundary loggers have the same pattern as the
pressures from loggers located inside the DMA, then the DMA is not hydraulically dis-
crete, and an unidentified cross connection to adjacent areas or a passing boundary
valve exists.
Once the integrity of the DMA has been confirmed it is necessary to measure the
total inflow to the DMA over several days to gain the necessary data to calculate the
existing volume of leakage and to estimate future leakage target volumes. This stage
should also be used to simulate fire flow emergencies to see if the selected feeder mains
have the capacity to provide sufficient flow during such an event. If it’s found that the
selected feeder main does not provide sufficient supply capacity during an emergency
then it is necessary to redesign the DMA and either change the boundaries or to include
an additional feeder main in the design.

16.6.4 DMA Meter Selection
The selection and installation of the DMA meters are key components when designing
and creating a new DMA. There are several key issues related to DMA metering that
need to be considered, such as the sizing of the meter, the ability of the meter to record
accurately at maximum and minimum flow rates, and the necessity to meet peak
demand and fire flow requirements. Fire flow demands for a DMA are dependent upon
the customer building demographics, since fire flow requirements vary notably between
residential structures and industrial, commercial and institutional customers such as
factories, shopping malls, schools, airports, and the like. Seasonal fluctuations and
demand changes are also factors that need to be considered when specifying the DMA
flowmeter.
The choice of meter size and type depends upon:

• Size of main
• Flow range
• Head loss at peak flows
• Reverse flow requirements
• Accuracy and repeatability
• Data communication requirements
• Cost of the meter
• Cost of ownership and maintenance requirements
• Water utility preference
When selecting the appropriate meter size and type, it is critical to assess the cur-
rent proportion of leakage to customer demand and to project the future reduced leak-
age rate anticipated to occur after leakage reduction controls are established. The
estimate of future leakage will affect the future minimum nighttime flow range. The
flow measurements conducted during the initial DMA installation and testing, in con-
junction with analysis of seasonal demand fluctuations and leakage, can then be used
to finalize the design of the DMA inflow meter(s) and meter chambers. Utilities with