All the major river systems of China, including the three longest--the Yangtze, Huang He, and Xi Jiang--flow in a generally western to eastern direction to the Pacific Ocean. In all, about 50 percent of the total land area drains to the Pacific. Only about 10 percent of the country's area drains to the Indian and Arctic oceans. The remaining 40 percent has no outlet to the sea and drains to the arid basins of the west and north, where the streams evaporate or percolate to form deep underground water reserves; principal among these streams is the Tarim.

The northernmost major stream of China is the Amur River (Heilong Jiang), which forms most of the northeastern boundary with Russia. The Songhua (Sungari) and Liao rivers and their tributaries drain most of the Manchurian Plain and its surrounding highlands.

 The major river of North China is the Huang He. It is traditionally referred to as ��China's Sorrow�� because, throughout Chinese history, it has periodically devastated large areas by flooding. The river is diked in its lower course, and its bed is elevated above the surrounding plain as a result of the accumulation of silt. The river rises in the marginal highlands of the Tibetan Plateau and follows a circuitous course to the Bo Hai (an arm of the Yellow Sea), draining an area more than twice the size of France. The Yangtze River of central China has a discharge more than ten times that of the Huang He. The longest river in Asia, it has a vast drainage basin. The Yangtze rises near the source of the Huang He and enters the sea at Shanghai. It is a major transportation artery.

Serving the major port of Guangzhou (Canton) are the estuarine lower reaches of the Xi Jiang, the most important river system of southern China. The river, which has numerous tributaries and distributaries, has a discharge three times as great as that of the Huang He.

Most of the important lakes (hu) of China lie along the middle and lower Yangtze Valley. The two largest in the middle portion are Dongting Hu and Poyang Hu. In summer these lakes increase their areas by two to three times and serve as reservoirs for excess water. Tai Hu is the largest of several lakes in the Yangtze delta, and Hongze Hu and Gaoyou Hu lie just to the north of the delta.

Saline lakes, many of considerable size, abound in the Tibetan Plateau. The largest is the marshy Qinghai Hu in the less elevated northeast, but several others nearly as large occur on the high plateau. In the arid northwest and in the Mongolian Steppe are a number of large lakes, most of which are also saline; principal among these are Lop Nur and Bosten Hu east of the Tarim Pendi. Ulansuhai Nur, which is fed by the Huang He, is in Inner Mongolia; Hulun Nur lies west of the Da Hinggan Ling in Manchuria.

More than 2000 reservoirs have been constructed throughout the nation, primarily for irrigation and flood control. Most are small, but the largest, the Longmen reservoir on the Huang He, has a capacity of 35.4 billion cu m (1250 billion cu ft).