The cost of constructing the necessary treatment facilities was estimated at between R10bn and R12bn, Minister for Water Affairs and Sanitation Nomvula Mokonyane said on Wednesday.
Mining companies will pay for 67% of the cost through a proposed environmental levy based on a "polluter pays" principle.
The project would augment the supply of safe and potable water, Mokonyane said at the launch of the project in Germiston.
Construction of plants that will further treat polluted water in the province is expected to begin in 2018, with the Treasury agreeing to contribute R600m per year to the project in expectation of the recovery of funds collected from the mining sector.
The cost to the consumer was fair, Mokonyane said, considering that improvements would be made to the province’s water supply, already a cost factor in an increasingly water-scarce province.
The acid mine drainage issue in Gauteng is a more than century-old problem that has seen water polluted with heavy metals rising to the surface through historic mine workings in and around the Witwatersrand Basin, which continues to pose a serious threat to existing underground water reserves.
In 2011, as a short-term solution, the Trans Caledon Tunnel Authority was tasked with pumping polluted water into three regional treatment facilities, partly treating it, and then pumping it back into the river system so that it was diluted with fresh water. This has been sufficient only to keep down the levels of underground polluted water so that it does not breach the surface.
The running costs of the facilities across the three basins in Gauteng was estimated at R25m per month, the authority’s CEO James Ndlovu said on Wednesday
The long-term solution will ultimately be to desalinate the water so that it can be used directly by industry and consumers.
An environmental impact assessment will be completed by June 2017, and the new plants are expected to begin to operate in early 2020.
The cost structure developed had been made in consideration of the importance of mining to SA’s economy, the minister said.
"Nothing is going to apply retrospectively; we are not on a witch-hunt," she said.
"Our regulatory environment has to be tightened, so that the polluter-pay principle is implemented."
Foundation for a Sustainable Environment CEO Mariette Liefferink said yesterday the foundation was "heartened" by the manner in which the department had taken up the issue. "However, we are still concerned regarding certain challenges, for example, the apportionment of liability. To hold only the last man standing liable and responsible for 130 years of mining may be inequitable and unpalatable," she said.
The Chamber of Mines said the proposed environmental levy and new infrastructure could cost more than had been proposed by the chamber. Treatment of water that was already pumped from mines on a cost-recovery basis, would not require new infrastructure, the chamber said.
With Charlotte Mathews