Western Cape Water Supply System

The Western Cape Water Supply System (WCWSS) is a complex water supply system in the Western Cape region of South Africa comprising an inter-linked system of six dams, pipelines, tunnels and distribution networks. Some elements of the system are owned and operated by the Department (Ministry) of Water Affairs and Forestry and some by the City of Cape Town. The principal dams are all located in the Cape Fold Mountains to the east of Cape Town. They are:

These dams are expanded upon on this page. In 2009, 63% of the water in the system was being used for domestic and industrial purposes in the city of Cape Town, 5% in smaller towns and 32% in agriculture.

Cape town supply dams are part of this circuit and with the drought experienced in June 2017, 2 of the dams Theewaterskloof and Voelvlei were at below average for this time of the year which necessitated water restrictions.

The largest component of the WCWSS is the Riviersonderend Government Water Scheme, which is a large inter-basin water transfer scheme that regulates the flow of the Sonderend River flowing South towards the Indian Ocean, the Berg River flowing North towards the Atlantic Ocean and Eerste River that flows into False Bay.

Its centerpiece is the Theewaterskloof Dam on the Sonderend River, the largest dam in the system with a storage capacity of 480 million cubic meter. It is linked to the Berg River via a tunnel system through the Franschhoek Mountains. During winter, when water requirements are lower, this tunnel system conveys surplus flows from the Berg River Dam and the tributaries of the Berg River to the Theewaterskloof Dam, where the water is stored. In summer, when water requirements are high, water can be released back via the tunnel system into the catchments of the Berg and Eerste River.

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