On Monday afternoon, Zille also met with South African Breweries at their Newlands facility, to discuss the bottling and distribution of 12 million bottles of water to parts of the City should the taps be turned off in residential areas.
Levels of usable water in the dams surrounding Cape Town have been dropping by 1.4 per cent a day, and now stand at around 17.2 per cent.
Authorities believe that "day zero" for the water situation will be 12 April.
The coastal city of Cape Town, located in the Western Cape of South Africa, has issued new water restrictions with the city now on the verge of running out of water.
Mokonyane was speaking as Day Zero is drawing near, threatening to make Cape Town the first metropolis in the world to run out of water.
When levels drop to 13.5%, the city of four million people will be forced to queue for daily rations of 25 litres from 200 water collection points - not even enough for a two-minute shower.
On Monday, Zille said that she had written to President Jacob Zuma, asking for a national disaster to be declared after the likelihood of Day Zero was confirmed by the City of Cape Town.
The limit will fall to 50 litres a day on February 1 - but the city's mayor, Patricia de Lille, said she feared they had reached the "point of no return". "Well‚ if they warned us then and it's their mandate to supply water‚ why didn't they do it?" said Zille.
California public health officials estimate that regardless of years of trying to reduce water use, state residents still consume an average of 88 gallons a day.
"Day zero has been heading in one direction and that's towards us", said Christine Colvin, a resident and freshwater expert with the World Wildlife Fund.
"We can no longer ask people to stop wasting water".
"The national government responsibility is bulk water supply".
Citizens are recycling bath water to help flush toilets and are being told to limit showers to 90 seconds.
"Defeating Day Zero has been and continues to be our main priority‚ and the work that has been done over the past year will continue with increased urgency to ensure we guarantee access to water for citizens‚" said Mokonyane.