The City of Cape Town advised residents that water in the distribution system is currently discoloured over a large part of the eastern, central and southern suburbs.
The discolouration is due to a process control fault at the Faure Water Treatment Plant.
As a safety precaution, residents are advised to boil the water before drinking especially if it appears discoloured.
The affected areas are being fed off the network from Blackheath Reservoir and the situation is anticipated to get back to normal over the next few days.
The City said it is working on resolving the problem as soon as possible, and apologised for any inconvenience.