Impacts of non revenue water on the national water supply and drainage board and methods to minimize it

Abstract

Non-Revenue Water (NRW) could be known as the gap between the volume of water which is put into a water supply system and the volume of water which is billed as authorized consumption. NRW is a major encounter to all the water utilities around the world since it affects upon water distribution systems. Except for limited number of Asian cities many number of cities have faced in to this phenomenon severely. Colombo is considered as the commercial capital of Sri Lanka and currently the NRW percentage of Colombo city has exceeded 45% which indicates that from the total amount of water supplied to the Colombo city, more than 45% of water which is supplied won’t generate revenue to the National Water Supply and Drainage Board. (NWSDB) The Government of Sri Lanka commenced a program on “Greater Colombo Water and Wastewater Management Improvement Investment program” with the recommendation of the National Water Supply and Drainage Board. Reduction of NRW within the Colombo city is extremely complex and tough since water distribution channel placed within the city is unsystematic and old. Replacement of System Input Volume (SIV) meters with electromagnetic meters for remote reading, rehabilitation of water distribution network by replacing pipelines, replacement of defective water meters, calibration and updating of the GIS network are some steps which are undertaken in this program. In conclusion this study will definitely provide revenue losses which should be borne by the NWSDB due to NRW and also the study will reveal minimization methods which are used currently in order to reduce NRW generation.