Water coming out of Durban's taps is safe to drink, authorities said on Wednesday, following reports of mercury contamination at Inanda Dam.

Umgeni Water spokesperson Shami Harichunder said: "The water is treated thoroughly and meets World Health Organisation standards. That water is safe."

Concerns over the city's water have arisen after the provincial agriculture and environmental affairs department warned people against swimming or fishing in Inanda Dam, one of Durban's main water supply dams.

People have also been warned against consuming fresh produce grown in the vicinity.

Agriculture and environmental affairs spokesperson Khulekani Ntshangase said there should not be any concerns about the city's water supply.

He said that hair samples from 16 people in the Umgeni River catchment area had revealed higher than normal levels of mercury.

He said further testing to include a greater number of people would be undertaken.

The Mercury newspaper reported on Wednesday that government officials had said tests on drinking water at Inanda for the past 10 years showed no level of danger for the general public and there was "no reason to panic".

The Mercury reported that a new report published by the Medical Research Council said there was evidence of higher-than-normal mercury levels in several people living around the dam, and 50 percent of fish samples from the dam were polluted with mercury at levels above the safe eating limits recommended by the World Health Organisation.

Ntshangase said it was not immediately known why there were increased levels of mercury.

He said he could not confirm whether the source of the mercury was the now defunct Thor Chemicals plant in Cato Ridge.

Rico Euripidou, an epidemiologist with the Pietermaritzburg-based environmental justice group "groundWork", said: "There is still a sludge dam and drums with a whole lot of waste."

British chemical giant Thor Chemicals (now called Guernica Chemicals in South Africa) imported hazardous waste with the aim of reclaiming the mercury.

At least three workers died and several others were poisoned after working at the Thor plant in Cato Ridge in the early 1990s.

The Cato Ridge plant was eventually shut down, but an estimated 3500 tons of toxic waste is being stored on the premises until a decision has been taken on how to dispose of it.

Sapa