the slums (1,242,490 m2) are located in northern Bogor, whereas their area is only 89,780 m2 in the southern part of the city. To improve this situation, the city administration launched a program of construction of cheap housing types (light prefabricated houses) in western Bogor. These houses combine reasonable rent ($22 per year) at acceptable living conditions. Electricity to Bogor is supplied by the Indonesian state company Perusahaan Listrik Negara, which serves the provinces of West Java and Banten. Electricity is provided by more than ten regional thermal and hydroelectric power plants via two local transformer stations located in the Bogor districts of Cimahpar and Cibilong. Whereas most of the houses (excluding some slum areas) are provided with electricity, street lighting covers only 35.38% of the city (4,193 light sources, as of 2007), however, the number of street lights is increasing at an annual rate of 10–15%. As of 2009, only 47% of Bogor is provided with clean tap water through a centralized water supply systems managed by state-owned Tirta Pakuan. The municipal system takes water from rivers Cisadane (1240 liters per second), and three natural sources: Kota Batu, Bentar-Kambing and Tangka (410 liters per second). Although the water network has a total length of 741 kilometers and covers about 70% of the city, connection to it is often problematic for financial and technical reasons. More than half of residents use water wells or natural reservoirs. Garbage collection service covers 67% of the urban area. From about 800,000 m3 of waste per year, about 90% is buried at an external landfill at Galuga, about 7% is recycled for compost and about 3% is burned in five incinerators within the city. The seven cemeteries of Bogor are named by the city districts as Cilendek, Kayumanis, Situgede, Mulyaharja, Blender, Dreded and Gunung Gadung. The first six have the status of "public cemeteries" (), and have no restrictions by religion or ethnicity. However, given the religious composition of Bogor, the cemeteries are predominantly Muslim, and Christian graves are located either in separate areas of cemeteries or in a small cemetery adjacent to churches. Some mosques also have small burial plots. Graves for the poor and nameless are mostly located at Kayumanis, and Gunung Gadung cemetery is restricted to Chinese residents. Education and science Bogor is one of the major scientific and educational centers in Indonesia. A significant part of academic and research base