a research on unaccounted water due to customer metering inaccuracies

unaccounted-for-water is a misleading term long used by water industry. unaccounted-for-water includes unmeasured volume of water that run out of access from supply to end consumer and consequently leads no revenue for supplier. examples of water losses are: meter inaccuracies, illegal connection and unauthorized usage of water, abnormal meter reading, reservoir seepage and leakage, reservoir overflow, underground leakage, pipe breaks, unwanted problem in the water treatment process, malfunction of distribution system controls, water consumption of hydrant. in domestic water network system, meter inaccuracies are one of the most important parts of unaccounted-for-water. through meter inaccuracies water consume by consumers but there is no payment. so many parameters could cause meter inaccuracies: erosion parts of meter, high water and environment temperature, suspended solid in inlet water, impure filter, low ended gears and unsuitable keep of meter in store. the solution for survey of meters in water system is meter testing. in this research a part of varamin with 6000 subscription and 4500 healthy meters was chosen as pilot of studies. one percent of meters choose randomly and the results were statistic analyzed .the results generalization to the whole city and total unaccounted-for-water was calculated. according to the results repair meter after 5 or 6 years is uneconomic and if after the test error of meter was found it should be changes with new one. in this region most of changing meter is repaired meter .before using meter the new meter and repaired meter should be test in the workshop and if has any problem should be back to the factory.87.5 percent of meter in the pilot area has no physical losses, 6.25 percent was in the standard limit and 6.25 percent gives more money to the supplier.