Soweto's electricity debt has been a headache for Eskom for decades, despite efforts to recover the money from residents.
The power utility's spokesperson, Dikatso Mothae, declined to share how far back Soweto's debt went and only described it as "historical".
"The debt is growing monthly due to nonpayment, short payments and increase of interest because of the outstanding debt on the individual accounts," she said.
But a source at Eskom told Sowetan that the debt was first passed from the City of Johannesburg to Eskom in 1993 and was written off in 1998.
He further said that new debt was accumulated after that and was again written off in 2003.
Mothae was also unable to state how the debt is spread across the sprawling township.
Mothae said Eskom has tried to curb the rise in the debt by installing prepaid meters but they were not helping.