Team member Lesley Green said: "None of us would like the results of our lab tests to be what they are in the context of this crisis."

But the City of Cape Town said it was confident that desalination plants in the Cape Town harbour, the V&A Waterfront, Strandfontein and Monwabisi, which are due to start operating in February, would produce safe water.

Xanthea Limberg, Cape Town's mayoral committee member for water and waste services, said desalinated water would have to meet the same standards as dam water.

"The water produced from desalination will be tested daily for conformance with the standard," Limberg said.

"Complex chemical pollutants will not be present in sufficient quantities to place the public at more risk than they would be just living in an urban environment where these chemicals are freely used."