Water Supply and Sanitation in Indonesia - Water Resources and Use

Water Resources and Use

Indonesia has over 5,590 rivers, most of them short and steep. Because of high rainfall intensities most rivers carry large quantities of sediment. Average rainfall is above 2,000 mm on most islands, except for the Lesser Sunda Islands where it is 1,500 mm. 80% of rain falls during the rainy season (October to April). While water resources are quite abundant in Sumatra, Kalimantan, Sulawesi, Maluku and Irian, water shortages occur during the dry season in parts of Java, Bali and the Lesser Sunda Islands. In particular in Java, the dry season flows are inadequate to meet the demand, leading to irrigation shortages. Irrigation accounts for 93% of water use. The total storage capacity amounts to only 5% to 6% of the river flows. Construction of reservoirs is constrained by lack of good reservoir sites, high density of population at possible reservoir sites and expected short reservoir lifetimes due to siltation. Groundwater potential in Indonesia is very limited. However, much of the eastern islands depend on groundwater because of surface water scarcity. Groundwater overexploitation occurs in heavily populated coastal areas of Java, including in Jakarta and Semarang. In Jakarta it has caused seawater intrusion up to 10 km from the coast and land subsidence at a rate of 2–34 cm/year in east Jakarta. In Semarang land subsidence occurs at a rate of 9 cm/year.

Water utilities abstract water from rivers and lakes (60%), springs (25%) and groundwater (15%). For example, the main water source for Jakarta is the Jatiluhur Dam on the Citarum River 70 km southeast of the city. For those who are self-supplied or receive water from community-based organizations, shallow groundwater and springs are by far the main sources of water on most islands. On Sumatra and Irian, however, rainwater harvesting is also an important water source.

Pollution. Domestic sewage, industrial effluents, agricultural runoff, and mismanaged solid waste are polluting surface and groundwater, especially in Java. Indonesia ranks among the worst countries in Asia in sewerage and sanitation coverage. Few Indonesian cities possess even minimal sanitation systems. The absence of an established sanitation network forces many households to rely upon private septic tanks or to dispose of their waste directly into rivers and canals. The commonality of the latter practice, together with the prevalence of polluted shallow wells used for drinking water supply in urban areas, has led to repeated epidemics of gastrointestinal infections.

Domestic Waste. According to Water Environment Partnership in Asia (WEPA), only 42.8 percent from 51,372,661 houses in Indonesia have domestic waste treatment. More than half of households dispose their domestic waste directly to the river body. Data from the World Bank shows that in 2008, only 52% of Indonesian population has an adequate access to excreta disposal facilities. Such facilities are important as they can help to minimize human, animal, and insect contact with excreta, thereby increasing the hygiene level and enhancing the living conditions for the slum-dwellers. Without proper construction and maintenance of these facilities, domestic wastes are disposed ineffectively and increases the rate of water resources degradation.

Industrial Waste. Industrial activities wastes such as small-scale industries, agriculture, textile, pulp and paper, petrochemical, mining and oil and gas also contribute to the degradation of water quality in Indonesia. Water quality in locations near to the mining areas is potentially contaminated by heavy metal such as mercury (Hg). According to WEPA, some level of mercury (Hg) concentration has been detected at 9 out of 16 sampling points and the highest level of dissolved mercury in one of the area reach 2.78 ug/l.

Therefore, the result of water quality monitoring in 30 rivers in Indonesia indicates that most of river water quality do not meet water criteria class 1, i.e. water that can be used for standard water, drinking water, and or other usage that requires the same water quality with such usage, due to pollution by domestic and industrial wastes (drinking water raw based on Government Regulation Number 82, 2001, Water Quality Management and Wastewater Controlling).