Page 45 - Water Loss Control

Understanding the Types of W ater Losses 27

large ICI users may experience dramatic differences in daytime and night time flows;
requiring meters that are accurate through a wide range of flow rates, that is, com-
pound type meters. Other factors place demands on the water supplier to provide accu-
rate metering. Some of the major reasons why water meters fail to measure water flow
accurately include
• Wear over time
• Water quality impact
• Chemical build up
• Poor finish and workmanship
• Environmental conditions such as extreme heat or cold
• Incorrect installation
• Incorrect sizing
• Incorrect specification of meter type for the application
• Tampering
• Lack of routine testing and maintenance
• Incorrect repair
Recommended maintenance practices for customer meters include monitoring
recorded consumption patterns and rotating the meter out of use on a regular basis for
testing, calibration, repair, or replacement.
Many systems use estimates of customer consumption for accounts where water
meters are nonexistent, defective, or unreadable. Estimates, which are used both tem-
porarily or permanently, can be inaccurate if they are not devised in a rational manner
or kept up-to-date with changing customer consumption patterns; hence another form
of inaccurate water measurement can occur here.
Meter reading is the next step in obtaining accurate water consumption data. Errors
in meter reading are essentially errors in measurement. With the growing use of auto-
matic meter reading (AMR) systems, the opportunity for meter reading error is probably
being reduced relative to that occurring in traditional manual meter reading opera-
tions. However, all systems seeking to optimize should include at least a brief assess-
ment of the accuracy of meter reading operations in transferring actual measured water
consumption into the information handling (billing) system.

How Errors in Water Accounting Occur
Errors in the handling of customer accounts can occur in a number of ways, some of
which include
• Customer water consumption data is modified during billing adjustments.
• Some customers who use water are inadvertently or intentionally omitted from
billing records and go unmonitored.
• Certain users are accorded nonbilled (free or subsidized) status and actual
consumption is not recorded.
• Human error occurs during data analysis and billing.
• Weak policies create loopholes in billing and water accounting.