A Study on improving the approaches to set the economic level of water losses in water distribution system

Abstract

The purpose of the research is to improve the methodologies for setting water losses targets applicable to local water supplies in South Korea. Recently, South Korea has been suffering serious water scarcity due to frequent droughts caused by climate change. Accordingly, Non-revenue water (NRW) reduction projects, given the uniform goals of NRW ratio either 15% or 20%, have been introduced as a countermeasure. The currently uniform water losses target does not take into account the different water supply conditions of local municipalities and should be revised with a proper rationale to determine the optimal water losses level. Through the literature review, the standardized methodologies for economic leakage target widely used in international countries and new approaches of South Korea were reviewed. MCW method, which is regarded as an applicable approach considering domestic conditions and an alternative of cumulative method are considered for the application. While MCW method revealed limitations as a result of the case study, the alternative method was able to calculate the economic leakage standard. MCW method was especially sensitive to data quality, and it was found that a clear relationship between the leakage level and the cost is not feasible considering domestic data characteristics. In addition, the effect of natural rate of rise of leakage and separation of effective NRW expenditure from total costs were identified as significant factors in calculating the leakage target. On the other hand, the cumulative method shows a more robust correlation than MCW, yielding the economic leakage target. Through the case study, the cumulative method is demonstrated to be more suitable than the MCW method. And consideration of natural rate of rise of leakages and the social and environmental cost and benefits are proven to be significant elements of leakage calculations. In particular, it was confirmed that further research was required to estimate the natural rate of rise of leakage accurately, as the water losses target can be substantially lower. Besides, due to the effect of the previously established multi-area waterworks system in South Korea, it is likely to result in the less marginal cost of water. If the social and environmental aspects are taken into consideration, the high water losses level will lower and eventually contribute to efficient water management. Lastly, two cases of a short-term and long-term perspective have been considered, but further research is recommended to establish multiple water losses targets varying with time changes.