in 1997, but the pilot project was not deemed successful and was stopped. DWASA's activities have been reorganised by the Dhaka WASA Act, 1996 that transformed DWASA into a service-oriented commercial organisation. Service area The service area of DWASA covers more than 360 square km with a population of about 12 million. It extends from Mirpur and Uttara in the North to Narayanganj in the South. Buriganga river and many canals flow through the city. Tropical vegetation and moist soils characterise the land, which is flat. The elevation of Greater Dhaka is 2 to 13 meters above the mean sea level, and most of the urbanised areas are at elevation of 6 to 8 metres. This leaves Dhaka susceptible to flooding during the monsoon seasons owing to heavy rainfall and cyclones. Challenges Water management in Dhaka faces numerous challenges such as flooding, poor service quality, groundwater depletion, inadequate sanitation, polluted river water, unplanned urban development, and the existence of large slums where more than one third of its population lives. Every year during the dry season, people demonstrate in Dhaka's streets demanding an uninterrupted supply of clean water. In 2010, Bangladesh's government had to even deploy troops to guard water pumps following angry protests. Flooding Bangladesh has been repeatedly exposed to severe flooding. Dhaka was particularly hit by the floods of 1970, 1974, 1980, 1987, 1988, 1996, 1998, 2004, 2007 and 2009, some of which such as the ones in 1988 and 1998 were catastrophic with flood levels of up to 4.5m in parts of the city. During the 1998 flood about 56 percent of the city was inundated, including most of the eastern and 23 percent of the western parts of the city. During non-catastrophic floods some streets are inundated for up to 60 cm for several days. Flooding in Dhaka is caused by high rainfall in the city and/or by flooding from the surrounding rivers and canals. The western and most densely settled part of Dhaka is protected from river flooding by raised roads and an encircling embankment built after the 1988 flood. The eastern part of the city where most of the expansion takes place consists of low-lying floodplains that are submerged during the monsoon season. When high rainfall coincides with a high water level in the river, stormwater cannot be naturally evacuated through the drainage system. Retention areas are supposed to mitigate flooding and pumping stations