Rand Water's overall reservoir storage capacity has dropped from 60% to 30% and the supply system could collapse if the water levels do not recover.

This is according to the Tshwane MMC for Utility Services Daryl Johnston, who described the situation as "very serious and, in fact, critical".

According to a statement on Monday, the MMC said a recent increase in water usage in the city prompted Rand Water to control water flow to the city.

He urged residents to reduce their water consumption urgently.

"If the situation does not change, the bulk water supply system of Rand Water will continue to drop and eventually collapse," Johnston warned.

According to the statement, this increased usage in Tshwane and other municipalities was linked to the recent heatwave, a lack of rainfall, and load shedding.

Johnston explained that load shedding affected the supply to water treatment plants by reducing pumping hours while the power was off.

He pleaded with residents to use water sparingly so that the impact of the current water challenges could be minimised.

The bulk water supplier notified Tshwane of its intention to "control the flow of water to Tshwane in order to reduce water consumption".

According to the MMC, Rand Water implemented restrictions to restore its overall reservoir storage capacity to normal operating levels.

Johnston further warned that unless water usage in the city was reduced and the capacity was restored, "more areas will soon start to experience water shortages".

Gauteng has faced water restrictions due to high consumption before.

In October, Rand Water tightened the taps due to high water consumption – often up to 5 000 megalitres of water a day – placing a constraint on the water supply to the province.