More than 400 million cubic meters of water will flow every year from the upper reaches of the Senqu River in Lesotho through the existing conveyance infrastructure to the Vaal Dam in South Africa.
South Africa receives water from Lesotho which feeds the Integrated Vaal River System, which ultimately supplies water to Gauteng and its surrounding areas.
More about the project, thanks to DM news: Lesotho highlands project: https://youtu.be/f21uPDGL1dA