Rainwater harvesting as an alternative of freshwater supply in Balikpapan city – a case study of Institut Teknologi Kalimantan

Abstract

Currently, 73% of the water demand in Balikpapan was only supplied from Manggar Reservoir, and it will continue decreasing parallelly with the increasing population. Regarding the population issues and the government’s planning for the new capital city of Indonesia, Balikpapan will be a buffer city facing serious risk in water supply issues in the future. Therefore, this study seeks to analyze an alternative of water supply. Following the concepts in Water Sensitive Urban Design (WSUD), The rainwater harvesting (RWH) method was chosen for preventive analysis, and Institut Teknologi Kalimantan (ITK) as one of the reputable’s universities in Balikpapan will be taken as a study location. The results obtained that the monthly water demand in ITK was ranged from 3228.34 m3 to 16632.97 m3. Using RWH, water supply analysis was obtained from 3790.62 m3 to 10697.31 m3 in various rainfall durations (0.5 to 2 hours) and 20 years projections (2022 to 2042). Following the obtained water supply. This study also reveals that the savings of total water usage can be reached from 24% to 100%, and around IDR 14,082,002 to IDR 37,035,390 is converted to currency. The highest saving reached due to water supply meets the water demand.