Page 272 - Water Loss Control

Contr olling Appar ent Losses—Systematic Data Handling Err ors 241

• Step 1: Analyze the workings of the customer billing system to identify
deficiencies in the water consumption data handling process resulting in
apparent losses. Flowcharting the data-handling pathways is a good way to
perform this analysis.
• Step 2: Compile listings of basic customer account demographics, including
number of meters by meter size, customer type, and consumption ranges. Look
for anomalies such as groups of small meters registering large annual
consumption volumes or large meter accounts registering unusually small
annual consumption volumes.
• Step 3: Perform meter accuracy testing for a sample of meter installations in
order to establish an understanding of the functional status of the meter
population (see Chap. 12).
• Step 4: Assess a sample of customer accounts or locations for unauthorized
consumption potential (see Chap. 15).
• Step 5: Identify accounting policies that have the potential to allow water to be
unbilled. Some billing systems have provisions to allow accounts to enter a
nonbilled status on the basis that the customer is, at least temporarily, not
consuming water. A vacant property is a good example. However, such
nonbilled accounts have been found to be a ripe source of apparent loss, as
many times poor record-keeping results in the customer remaining nonbilled
even after water consumption has resumed.

It is recommended that the billing system analysis always be performed as the initial
step, since gaps in this process could affect the data that is evaluated in the other steps.
For most drinking water utilities the customer billing system serves as the source of
all customer data, including water consumption. Early in the development of the water
loss control program, the auditor should develop a detailed understanding of the ways
in which consumption data is managed in the customer billing system. Constructing a
series of flowcharts that outline the various information handling processes is a system-
atic approach that can reveal gaps in policy, procedures, or programming that may
allow apparent losses to occur. Any such deficiencies that allow customers to exist with-
out billing accounts, without accurate metering and meter reading, or allow metered
consumption data to be unduly modified, can create apparent losses.
Figures 14.2 to 14.5 represent several customer billing system flowcharts for the
City of Philadelphia. The Philadelphia Water Department and Water Revenue Bureau,
an office of the city’s Revenue Department, together manage the customer billing pro-
cess. Figure 14.2 gives a flowchart that represents an overview of the entire billing pro-
cess. While it displays the major billing functions at a glance, it lacks sufficient detail to
identify likely occurrences of apparent loss. Additional flowcharts that display indi-
vidual sub-processes of the customer billing system are given in Figs. 14.3 to 14.5. In
these flowcharts the meter reading sequence for both automatic and manually read
customer meters are shown, as well as the meter rotation (replacement) process.
Although Philadelphia installed the largest water utility AMR system in the United
States from 1997 to 1999, approximately 2% of its customer accounts await AMR due to
access issues or the need to address large meter sizing/piping constraints. Therefore
Philadelphia utilizes both automatic meter reading and, to a much smaller degree, man-
ual meter reading. Using flowcharts to assess various subprocesses of billing operations