Bulk water supplier Rand Water is pumping water at full capacity at Eikenhof, but water systems in the city are still under "tremendous strain", said Johannesburg Water's spokesperson, Puleng Mopeli, on Friday.
Major reservoirs and towers - Crosby, Brixton and Hurst Hill - are critically low.
The Forest Hill Tower is empty, but the Eagle Nest system is currently stable.
In a statement, Mopeli said systems were low to empty due to Rand Water's implementation of Stage 2 restrictions.
The "highly impacted systems" are Alexander Park, Heldekruin, Honeydew and Linden, which remain at critical to low levels.
The Alan Manor, Glenvista and Naturena reservoirs have, however, recovered.
"Customers are urgently requested to reduce water consumption, as this will assist with recovering constrained systems. While customers in lower-lying areas may still have water, other customers in higher-lying areas are without supply.
"Customers are advised to report leaks and bursts in the area, which may impact on the recovery of the affected system," Mopeli added.
He said the systems were being monitored and further updates would be provided to residents.
Stage 2 water restrictions must be adhered to, according to section 44 (3) of the Water Services By-Laws.
Under these by-laws, all customers are compelled:
- Not to water and irrigate their gardens from 06:00 and 18:00 every day;
- Not to fill their swimming pools with municipal water; and
- Not to use hosepipes to wash their cars, paved areas, etc.
- Don't leave taps dripping,
- Take shallow baths
- Use bathwater or grey water to water the garden.