"The city would like to caution residents against making use of water from the Inanda Dam after reports that the large spill of caustic soda from the Msundusi River has worked its way downstream into the dam. Caustic soda is a very alkaline material and is therefore corrosive.

"Residents upstream of the dam and in the dam surroundings are advised not to expose themselves to the water in the river nor should they allow livestock to drink such water until further notice," said spokesperson Msawakhe Mayisela.

He added that residents would be informed once the water was safe.

"We are also worried about reported incidents of livestock being affected. What is more concerning is that this happened right when we were holding a climate-change summit that dealt with, among other things, the pollution of our rivers and water sources," Dube-Ncube said.