Johannesburg Water (JW) said some of its systems are unable to meet the growing demand, despite reconfiguration interventions.
The entity said it is closely monitoring reservoirs supplying Westbury, Westdene, Melville, Auckland Park, Emmarentia, Sophiatown, Coronationville, Claremont and CrownGardens.
Some reservoirs are either low or empty, while others have recovered.
JW said as if Wednesday evening, although low, the Brixton tower is receiving supply.
Hursthill 1 is on bypass and dependent on inflow, while Hursthill 2 is empty.
Linden 1 is currently low with the tower empty.
In flow at the Crosby reservoir has improved, with the level remaining stable and both pumps running.
The Brixton reservoir is stable, with one pump running.
Systems that have satisfactory capacity and supplying are Linden 2, Waterval tower, Quellerina, Crown Gardens, Corriemoor, Fairlands, Erand 1 in Midrand.
Erand 2 and the Grand Central system was dropping on Wednesday, due to high demand.
Picture: Johannesburg Water is investing around R3 billion for the upgrade of the Commando System project (Crosby, Brixton, and Hursthill reservoir & tower complexes).