Today ‘s world water problem may be due to absence of water , inaccessibility to water source in community but 10% of the problem may be due to water losses in the different communities around the world. Everyday litres or gallons of water are lost through leakages on pipes, runoff, wastage etc. These leakages/runoff though rarely put into consideration contribute to about 10% of the world water losses which is termed as non revenue water.
Nonrevenue water is the portion of the water that a utility places into the distribution system that is not billed and, therefore, recovers no revenue for the utility. Nonrevenue water consists of the sum of unbilled authorized consumption (metered and unme-tered), apparent losses, and real losses. It is recommended as best practice by the IWA and AWWA WLCC that the assessment of real losses using a “top-down” water balance should be complemented by at least one of the following two methodologies:
• Component analysis of real losses, a technique which models leakage volumes based upon the nature of leak occurrences and durations (see Chap. 10)
• “Bottom-up” analysis of real losses using district metered area (DMA) and minimum night-time flow (MNF) analysis (see Chap. 16)
Both methodologies add increased refinement and confidence in the calculated volume of real losses and are described separately in this manual.