"The acid mine drainage crisis in Gauteng has been mishandled from the start, characterised by inexcusable delay and policy zig-zags," he said.
Bloom was responding to a Sunday Times report that government planned to pump partially treated acid mine drainage (AMD) into the Vaal River.
Competent oversight was needed to ensure the Vaal's water quality did not deteriorate unacceptably, he said.
"Meanwhile, projected costs have escalated alarmingly, more than doubling … as announced recently by Water Affairs Minister Edna Molewa."
Earlier, the weekly reported that underground pumps would be used to pipe water from the central basin — underneath Johannesburg — into a treatment plant where it would be partially cleaned, or neutralised.
This water would then be released into the Vaal, diluted with clean water from the Lesotho Highlands Project to minimise the harmful impact.
"Pumping neutralised [acid mine water] into the Vaal River is a short-term intervention necessary for environmental and socio-economic protection," water affairs spokesperson Sputnik Ratau told the paper.
He said this solution was only temporary, and had been standard practice during mining's peak period.
Water quality would be monitored and regulated, he said.
Molewa gave the treatment plan emergency status two weeks ago.
However, the pumping plan had been approved without studying the potential impact on the river, prompting criticism from environmental groups, the weekly reported.
About 800km of empty mine tunnels and shafts beneath Johannesburg are filling up with acid mine water.
This water is expected to reach the Gold Reef City theme park by June next year.
Water becomes acidic when in contact with mined rock surfaces. – Sapa