Non-Revenue Water (NRW) and its handling for a drinking water supply system in Kedewatan zone Gianyar Bali

Non-Revenue Water (NRW) is a common issue of drinking water supply system. NRW can be detrimental that should be addressed properly including NRW rates, NRW caused, and a guidance for preventing and reducing NRW. The water loss measured through water balance that calculated the percentage for differences the water distribution (m3) with the water recorded (m3) on the bill. Infrastructure Leakage Index (ILI) used to calculate the physical water loss based on the standard target matrix of IWA (International Water Association). The causes and handles of NRW were analysed based on a step test result, Ultrasonic Flow Meter (UFM) test result, and interviewing PDAM staffs. The result of NRW rates reach 986,884.92 m3/year (65.53 %). The ILI index was 69.98, and the water pressure was 17.2 m. As a result, this zone included D category, that has high of water loss rate > 200/s/connection/day. In this zone, the causes of water loss are categorized into the physical and non-physical water loss, and the mitigation must be carried out according to the type of water loss occurred. PDAM Gianyar should investigate the possibility of non-physical water loss so that can reduce the level of water loss and the ILI value. The further research can be conducted an evaluation of the whole network with the purpose of NRW can be calculated maximally.