Theewaterskloof Dam's earth-fill wall is 646 metres (2,119 ft) long and 35 metres (115 ft) high. An inlet tower and conduit through the wall allow for releases of water into the Sonderend River. The spillway can handle a maximum flood of 394 cubic metres per second (13,900 cu ft/s). The Charmaine intake tower draws water from the reservoir into the Franschhoek Tunnel, which conveys it under the Franschhoek Mountains into the Berg River catchment and ultimately into Cape Town's water supply. In winter the tunnel can operate in reverse, conveying surplus water from the Berg River into Theewaterskloof. An additional intake tower supplies water to the Vyeboom Irrigation Board for irrigation of areas around the dam.
