Mpumalanga residents living in low-lying areas and next to flood lines have been warned to move to higher ground as the rains in the province continue.
"The provincial local government ... has instructed all municipalities to be on full alert," a spokesman said yesterday.
He advised residents not to cross rivers, either by foot or by car, if the water level was rising.
Road users were also warned to be careful as the roads were wet and in some areas rocks had fallen on the road.
Two dams near Standerton were between 114 percent and 150 percent full, weather officials said.
Meanwhile, at least 22 people have been swept to their death by floodwaters in Mozambique, and one person has been killed and at least 1 000 people displaced in Malawi.
Mozambique officials said the death toll had risen sharply from the initial eight reported a week ago, and heavy rains were expected to continue.
Rains had fuelled the spread of disease, with 114 cases of cholera reported in the Sofala region. But the crisis had been contained and there were no deaths from cholera, state administration minister Lucas Chomera said.
Officials said Mozambique's major rivers remained near the seven-metre flood alarm level but were not a concern at the moment.
Weather services predicted rain would continue to fall over the entire week.
Rains damaged roads and other infrastructure, officials said, making it difficult for relief workers to distribute food to some 800 000 people cut off in the Sofala and Gaza regions where stocks were declining fast.
The Limpopo railway, linking neighbouring Zimbabwe to Maputo port, had also been closed after rain-induced damage and weather prevented planned repairs. - Sapa, Reuters