The backlog went from R38b in 2006/2007 to R68bn according to a study, the department told Parliament on Tuesday, the Star reported on Wednesday.
Energy department acting director general Wolsey Barnard said outages like the one in Johannesburg on Monday, were caused by poor maintenance.
“If we keep doing the wrong things we are doing, not maintaining infrastructure, we will continue to see the trend,” he was quoted as saying.
The problem would require fixing of distribution lines, substations and switch gears.
One metro in Gauteng had 400 outages between July 2013 and June 2014 because of poor maintenance of infrastructure, he said.
These had nothing to do with Eskom.
He told journalists on the sidelines that lack of maintenance had been due to lack of money by municipalities — who were not using money on the tariff structure to fix infrastructure.