The country's top official anti-graft watchdog is recommending Zuma repay some of a $21 million publicly funded "security upgrade" to his private home, which included a swimming pool and marquee area, a newspaper reported on Friday.
The Mail and Guardian weekly said the Public Protector's provisional report, entitled 'Opulence on a Grand Scale', found Zuma had derived "substantial" personal gain from the home improvements paid for by the state.
Zuma's spokesman declined to comment on the newspaper report. No one was immediately available to comment from the office of Public Protector Thuli Madonsela.
The leaked findings of an investigation by the official anti-corruption watchdog into Zuma's Nkandla residence could be damaging to Zuma and the ruling African National Congress (ANC) six months before an election.
The newspaper said the improvements made to Zuma's home included a visitors' lounge, amphitheatre, cattle enclosure and swimming pool, referred to in Public Works documents as a 'fire pool' on the pretext it could double up as a water reservoir for fire-fighting purposes.
The government went to court this month to try to prevent Madonsela from releasing the investigation report, on the grounds that cabinet ministers needed more time to work out whether its findings jeopardised Zuma's security.
It quickly dropped its challenge after Madonsela insisted she had gone to great lengths to ensure the report did not pose any threat.
The Mail and Guardian said Madonsela's report accused Zuma of violating two executive ethics codes - failing to protect state resources and misleading parliament.
Zuma, a polygamous Zulu traditionalist whose first five years in office have been littered with scandals, told parliament last year all the buildings in the sprawling compound in rural KwaZulu-Natal province had been built "by ourselves as family, and not by the government".
The report also found some of the more legitimate security features, such as 20 houses for police protection, a clinic and two helipads, were excessive and should have been placed in a nearby town to benefit the broader community, the paper said.
The paper estimated some of the questionable features of the upgrade at 20 million rand.
It also said that Zuma ordered his private architect be drafted in as "principal agent" to oversee the upgrade, even though he was not a security expert.
In comparison, the 215 million rand spent on Zuma's home is in stark contrast to state money spent on improving the security of previous South African presidents, the Mail and Guardian said.
FW de Klerk, South Africa's last white president who left office in 1994, received 236,000 rand for upgrades to his house, while 32 million rand was spent on Nelson Mandela's home.