JOHANNESBURG, Oct 12 (Reuters) - The South African government denied on Friday that sewage had spilled into rivers in Gauteng province, home to the country's business hub Johannesburg.

The department of water affairs said on state broadcaster SABC untreated water rather than sewage had spilled into the rivers, and drinking water in the province was still safe.

"Gauteng is very well serviced...communities have access to water from taps and therefore the damage is very minimal, the risk is very minimal to the community," said Hilgard Matthews of the department of water affairs.

The department said its environmental studies had shown the water was not harmful and people were not at risk.

Reports on Thursday had blamed the spillage on power outages, raising fears drinking water could be contaminated.

South African cities have suffered a number of power outages as demand outstrips supply and infrastructure is ageing.

State power utility Eskom [ESCJ.UL] has proposed raising electricity prices by 18 percent to fund an upgrading programme.

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