The City of Cape Town anticipates that its supply of municipal water will run out around March 2018, Mayor Patricia de Lille said on Wednesday.

"If consumption is not reduced to the required levels of 500-million litres of collective use per day, we are looking at about March 2018 when supply of municipal water would not be available," she said at the unveiling of the city's critical water shortages disaster plan.

"The day or month of this happening is, however, not as important as what we do now to avoid such a time."

The current collective water use stood at 618-million litres per day. As of Monday, October 2, the useable water left in dams stood at 27.6%.

De Lille detailed the various ways in which the city was finding other sources of water and clamping down on delinquent water users.

New water schemes were expected to come online by around December/January, if all went according to plan.

Water from temporary land-based desalination plants in Monwabisi and Strandfontein were expected to come online by February 2018.

From March 2018, additional desalination plants were set to come online.

Additional water from ground water extraction at the Atlantis and Silverstroom aquifers was expected from January/February in 2018.

De Lille was optimistic after a meeting with Water and Sanitation Minister Nomvula Mokonyane earlier on Wednesday.

"She was very supportive. We have raised a couple of issues with her. She has promised she will help," De Lille said.

"I want to assure all residents that we will not let a well-run city run out of water."