Water shortages are a chronic and severe problem in much of South Africa. The country has no commercially navigable rivers and no significant natural lakes. Along the coastline are several large lagoons and estuarine lakes, such as Lake Saint Lucia in KwaZulu-Natal. The government has created several artificial lakes, primarily for agricultural irrigation.

South Africa's largest river, the Orange River, rises in the Drakensberg Mountains and flows to the west and northwest, draining the highlands of Lesotho before being joined by the Caledon River between the Eastern Cape province and the Free State. The Orange River forms the border with Namibia before emptying into the Atlantic Ocean.

The major tributary of the Orange River, the Vaal ("foul"--for its murky cast) River, rises in the Drakensbergs and flows westward, joining the Orange River from the north in Northern Cape province. Together, the Orange and the Vaal rivers drain almost two-thirds of the interior plateau of South Africa. Other major rivers are the Breede River, the Komati River, the Olifants River, the Tugela River, and the Umzimvubu River, which run fairly short distances from the interior plateau to the ocean, and the Limpopo and Molopo rivers along the northern border with Botswana and Zimbabwe.