JOHANNESBURG - Joburg Water is worried after preliminary test results on its water.
It came after residents complained of a foul smell from their taps.
The agency is warning residents in the CBD and Bez Valley not to drink tap water.
READ: Residents warned not to drink tap water in parts of Joburg
As a precaution, it's isolated supply and is providing tankers to affected communities.
"As far as estimated restoration for this incident, we cannot confirm because the laboratory results take time," said Joburg Water operations manager Gugulethu Quma.
He said as soon as the water reaches the drinking standard, they would be able to release the water.