Methane bubbles popping on the river's surface, sewage pipes clogged with tampons, diapers and toilet paper, and the smell of faeces lingering in the air.
These scenes are everyday realities for residents of Emfuleni - a municipality southwest of Johannesburg - as the breakdown of the area's pipes, pumps and wastewater treatment plants causes sewage to overflow into one of South Africa's largest rivers.
As the government announced a major plan in November to address the wastewater crisis and an ongoing drought, residents told the Thomson Reuters Foundation the seeping sewage is making their homes unliveable and their children sick.
"This is a national crisis," said colonel Andries Mokoena Mahapa from his temporary office in the city of Vanderbijlpark near the Vaal River, where the South African army was dispatched to assist with sanitation repairs last year.
"We have seen children playing in the raw sewage," he said. "Old people who can't buy groceries because they can't cross the river of excrement to get to the shops. These are only a few examples. It has been very alarming for us."
Under global development goals agreed in 2015, governments pledged to provide access to clean water and sanitation for all by 2030.
But three in 10 people worldwide still do not have access to a water source free from faecal and chemical contamination, according to a 2017 report by the World Health Organisation and UNICEF.
Much of South Africa, a water-scarce country, still suffers from poor water management, according to South African think tank the Institute for Security Studies.
"The government needs to urgently prioritise funding so that (it) can restore the lives and the dignity of the people of the Vaal," Mahapa said, citing "poor governance" as a major cause for the system's collapse.
He added the army's mandate until January would involve safeguarding infrastructure from theft while it waits for repair work to be taken over by the Ekurhuleni Water Care Company (ERWAT), which is commissioned by the government.
Citing "urbanisation, ageing infrastructure and limited municipal maintenance capacity" as reasons for the worsening conditions, sanitation department spokesman Sputnik Ratau said that 1.1 billion rand ($75 million) had been earmarked for repairs.
But it was not clear when the work would start, he said in a phone interview.
ERWAT did not respond to several requests for comment.