Large parts of Johannesburg have been without water since Tuesday evening and the cause is anyone's guess.
Johannesburg Water tweeted that it was experiencing "challenges with our Bryanston reservoirs. The reservoir levels are low and therefore we had to close the outlet".
According to Isaac Dhludhlu, Johannesburg Water spokesperson, the cause of the problem has not yet been determined.
"We are still investigating," Dhludhlu told News24 on Wednesday. "The water that goes into the reservoir is not enough, so we have lost pressure and capacity in the reservoir.
"However, we don't know the cause. We are still checking with Rand Water whether the supply from them is enough for our reservoirs and we are investigating whether there might be a leak somewhere that is causing this problem."
Areas that are affected by the outage include Bryanston, Epsom Downs, Palmlands, Douglasdale, Fourways, Lonehill and Magaliessig, and surrounds.
According to Dhludhlu, it appears that "quite a big area" is affected.
Dhludhlu said roaming water trucks had been sent to affected areas "until such time as we can determine the problem. Then we can advise on the way forward".
Because the cause of the problem has not yet been determined, Dhludhlu could not say when water to the affected areas would be restored.
"As soon as we know, we will communicate this on our Twitter page," Dhludhlu said.
According to Johannesburg Water's Twitter page, water tanks would be available at Nicolway Shopping Centre, Epsom Downs, Douglasdale, Fourways/Fourways Mall, Pineslopes Shopping Centre, Leopard Frog and Lonehill Boulevard.
There will also be roaming water tanks in the affected areas.
Last month, a substation that provides electricity to the Rand Water infrastructure that pumps water to approximately 40% of Johannesburg, as well as parts of the West Rand and Rustenburg, caught fire in an apparent act of sabotage. Water supply to many suburbs was interrupted.
Isaac Mangena, City Power spokesperson, told News24 at the time that the damage was so severe that under normal circumstances, it would have taken at least 72 hours to repair.
Supply was however restored within 32 hours.