Page 257 - Water Loss Control

230 Cha pte r F o u r tee n

assist water loss control programs, by separating components of authorized consump-
tion from components of loss. Beyond their financial purpose, customer billing systems
have also come to be relied upon for these important engineering purposes. Unfortu-
nately, many systems were designed with only the financial function in mind, and water
utilities that now also use billing system data for engineering purposes may be doing so
without knowing whether adequate controls exist to ensure the engineering integrity of
customer consumption data.
It is important that water utility managers understand the workings of the cus-
tomer billing system with regard to consumption data integrity. Many billing systems—
while configured with sound billing intentions—may unknowingly corrupt the
engineering integrity of water consumption data. Some systems, when generating a
credit to the customer, back calculate the adjustment by changing the actual meter read-
ings or consumption. A monetary credit to the customer is thereby triggered by reduc-
ing, eliminating, or creating negative consumption values for the period in question.
Frequent adjustments in this manner can greatly distort the true amount of consump-
tion for individual customers or whole communities. Other programming features in
customer billing systems—while created with good financial intention—might unin-
tentionally corrupt consumption data in an engineering sense.
It is recommended that sufficient controls be designed into the customer billing
systems if the system is to be used for both billing (financial) and operational (engi-
neering) purposes. This will protect customer consumption data integrity while pro-
viding proper billing functions. The primary function of most existing customer
billing systems is to accurately account for the revenue received by the utility for ser-
vices rendered to individual customers. Utility operators embarking upon conserva-
tion, hydraulic modeling, or water loss control programs should undertake a careful
review of the billing system function and configuration to ascertain that the actual
consumption amounts are not unintentionally modified by billing operations, and
that the customer consumption amounts recorded as output of the billing system are
unchanged from the data generated by customer water meters. The utility should
undertake a flowcharting exercise of the billing process, as detailed later in this chap-
ter, in order to identify any impacts to customer consumption integrity, as well as to
identify any apparent loss components from the data-handling process. If consump-
tion data is found to be modified by billing operations, the utility manager should
consider reprogramming the billing system to record both the registered consumption
and billed consumption as separate fields, thus ensuring that the accuracy of billing
functions and customer consumption data are preserved. Until this is implemented,
an estimate of the impact of such adjustment activity should be included as a compo-
nent of the apparent losses.

14.3 Adjusting for Lag Time in Customer Meter Reading Data
Corrections must be made to metered use data when the source-meter reading dates
and the customer-meter reading dates do not coincide with the beginning and ending
dates of the water audit period, which is recommended to be a 1-year period.

Adjusting for one meter route. For example, a utility is studying one calendar year,
January 1 through December 31. Source meters are read on the first day of each
month and customers’ meters are read on the tenth day of each month. The goal is
to calculate the amount of water supplied and consumed for the calendar year.