Reducing Water Loss Based on Water Balance Method (By Using Step Test - Sounding Technique) and Financial Analysis (Case Study: Graha Indah Residence, PDAM Tirta Manggar In Balikpapan City)
Authors:   Program Studi Teknik Lingkungan, Fakultas Teknik Sipil dan Perencanaan, Universitas  Balikpapan, Indonesia, Rengganis Sekar Inggar , Notodarmojo Suprihanto ,   Program Magister Pengelolaan Infrastruktur Air Bersih dan Sanitasi, Institut Teknologi  Bandung, Indonesia
Published: May 2022

Abstract. The most common problem that occurs in the distribution of drinking water supply caused by the high rate of water loss or Non-Revenue Water (NRW), no matter how much the water loss is, it is causing a lot of disadvantages for the PDAM and has greatly affects for the company's performance. One of the efforts of PDAM Balikpapan in improving the drinking water supply system is to establish the District Meter Area (DMA) to optimize of water loss controlling. This study is located in 2 (two) District Meter Areas (DMA) namely DMA Graha Indah 1 and DMA Graha Indah 2 where the selection of study locations is based on the largest water loss rate among DMA systems in Balikpapan City. The DMA system aims to divide a wide distribution system area and hydraulically isolate the system so that it only has 1 input system. The loss of water from the results of the Balikpapan City PDAM Report 2015 for Graha Indah residence amounted to 35.44%. This research using the Water Balance Method (WB) as the main method that consists of water meter reading, step test-sounding technique, pipe repair and also using ILI as an indicator of physical loss meanwhile for non-physical loss using water meter accuracy. This study also discusses the simulation of existing network hydraulics (using the WaterCAD software V8i) as an approach to indicate water loss based on pressure along the pipeline. In attempting to reduce water loss in the Graha Indah residence, 3 scenarios in which all scenarios left 5% non-physical loss results in increased accuracy of water meter reading using an Android-based application which is an effort to reduce non-physical loss from data component error handling sub-component, then for water meter inaccuracy and illegal connection sub-component entered into the calculation in the planned scenario 100% reduction in losses non-physical water with inaccurate efforts to renew water meters and control illegal connections. Then for the remaining physical losses of 10%, 7.5% and 5% in each scenario with efforts to reduce physical water loss is to repair leaks in service pipes in both DMA. The results of research at both DMA shows that the water loss rate is quite high, namely for DMA Graha Indah 1 46.94% or 163,012 m3 (127,159 3 physical loss; 35,853 m3 non-physical loss) and DMA Graha Indah 2 is 59, 2% or 211,017 m3 (184,596 m3 physical loss; 26,420 m3 non-physical loss). The results obtained after the pipe repair has decreased as much as 4% for DMA Graha Indah 1 and 41.16% for DMA Graha Indah 2. The selected scenario is based on financial feasibility with a 5-year analysis period (i = 4.98%). The results of financial feasibility proves that scenario 3 is a selected scenario for DMA Graha Indah 1 which NPV, BCR, and BEP values respectively Rp. 9,430,810,135; 3.3295; 0.1086 and for DMA Graha Indah 2 the chosen scenario is scenario 3 which NPV, BCR, and BEP values respectively Rp 8,417,476,299; 2.767; 0.146. Keywords: Water loss, DMA, WB Method, Step test, Sounding, Simulation, Financial feasibility