Water hyacinth is flourishing in the Vaal River, Joburg's only source of water

The Integrated Vaal River System is an essential water source serving 19 million people in Gauteng, the Free State, the Northern Cape and the North West provinces through 14 dams, purified by Rand Water.

Bugs have been unleashed as bio-weapons in the Vaal River to help stave off invasive plants flourishing on the water.

Despite the importance of the water source, tonnes of sewage was allowed to flow unabated into the rivers for years because of the wastewater treatment plants in Emfuleni.