These areas form South Africa’s economic heartbeat, but Rand Water, the bulk water supplier for this region, did not answer questions about the impact of sewage and other pollution on their drinking water supply from the Vaal Dam. They said the questions fell under the competence of the Department of Water and Sanitation but failed to respond. However, a water quality specialist at Rand Water, who cannot be named for fear of losing his job, issued a dire warning if the matter is not addressed.
He explained that while pollution within the Vaal catchment has had serious environmental impacts over at least the last decade, it has not yet affected water purification capabilities or costs. He said this is because the microbiological component – the E.coli and related gut bacteria – does not last long outside the human gut, so it was not a factor by the time the water flowed to the Vaal Dam, and even if it was, it would be killed by chlorine.
However, the chemical component, the nitrates and phosphates, do remain. The water purification process is designed to remove these elements within a wide margin of concentration and he said we are currently “fairly far” from exceeding these margins. This is partly because the Vaal Dam is so large, which allows for sufficient dilution, and partly because a good rainfall season, such as the last two in a row, has prevented the build-up of chemicals.
“The simple answer is that the cost (of water purification) is not affected, but if it gets to that point, it would be drastic,” he said.
Although this might be a decade or more away, he said he was not hopeful it would be avoided. He pointed to increased pollution from continued municipal dysfunction married with population growth, a failure to deal with acid mine drainage and agricultural runoff, combined with a few years of drought as experienced by Cape Town in 2017, as factors that could push the Vaal Dam to a point of eutrophication. This occurs when an influx of nutrients, like nitrogen and phosphorus, stimulates algal growth to the point where oxygen is removed from the water making it incapable of supporting life. Eutrophication also leads to blooms of cyanobacteria (commonly known as blue-green algae) which produce toxins that can be fatal. Studies show that once a water body has become eutrophic, it may take a thousand years for it to recover.
The Rand Water employee said eutrophication of the Vaal Dam was “a long way off,” but warned that “if we get to that point,” there would be nowhere else to go in terms of water supply for the roughly 10 million people who rely on the dam for drinking water.
However, Anthony Turton, a Professor at the University of Free State’s Centre for Environmental Management, who is also a specialist in acid mine drainage, said there was “no question” the Vaal Dam was already moving toward a eutrophic state.
Turton cited several studies showing around 60% of large dams in South Africa had become eutrophic and said “we’ve never managed to turn it around.”
He explained that current bulk water treatment methods cannot remove the toxins produced by blooms of cyanobacteria. These toxins, he said, have been proven to injure motor neurons in the brain, impairing cognitive function. They can also cross the placenta, bioaccumulating in the fetal brain.
Turton did point out that water from a eutrophic dam can be purified to drinking water quality through charcoal activation or advanced oxidation but said neither of these methods was currently in use.
What is clear is that while Johan Lotter and his parents continue to have to live in a faecal swamp, a national water security crisis is creeping ever closer with each kilolitre of untreated sewage that flows into the Vaal from these failing municipal systems.
Contracted worker Vusi Langa sweeps up dirt after trenches were dug for the refurbishment of a sewerage line running down Standerton’s Coligny Street. The repair is one of few bright spots in the system as residents have been suffering spillages into their yards for a number of years amidst the general collapse of the sewerage network.