In the urban areas of Indonesia, most of the low-income population lives in kampungs. Almost one-quarter of the city area of Surabaya, an industrial metropolis with a population of about 2.5 million, is covered by them. Kampung Kebalen has an average density of 800 people per hectare living in densely packed single-storey wooden houses within networks of narrow alleys. The average monthly household income is US$ 35 to US$ 65. Potable water, electricity and sanitation were lacking. Flooding occurred during the rainy season. The city upgraded Kampung Kebalan by adding footpaths, drainage, water and sanitation, efficiently constructed within a six-month period. The improvements cost US$ 400'000. All funds were from the government of Surabaya with a loan from the World Bank.