Administrative divisions of China By its political level, when a "city" is referred to, it can be a: By its actual area and population, it can be: When used in the statistical data, the word "city" may have three different meanings: It is important to specify the definition of "city" when referring to statistical data of Chinese cities, otherwise, confusion may arise. For example, Shanghai is the largest city in China by population in the urban area but is smaller than Chongqing by the population within the administration area. Before the establishment of the Qin Dynasty, China was ruled by a network of kings,
Water supply and sanitation in China built in the city of Nanjing. Subsequently, China engaged in what is possibly the largest wastewater treatment investment program in history. It has been estimated that in 2006 there was sufficient capacity to treat 52% of municipal residential wastewater. According to the State Environmental Protection Agency the rate of urban wastewater treatment reached 57% in that year. The government's goal to achieve a level of 60% for treatment of municipal wastewater by 2010 was surpassed. By 2010, 77.5% of domestic waste water was treated. Between 2001 and 2004, the number of cities that charge wastewater tariffs has increased from 300