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.
It had been 22 April, but it has been brought forward as water levels at dams in the region continue to drop week after week, with the overall amount of usable water now falling to 17.2%.
"Despite our urging for months, 60% of Capetonians are callously using more than 87 litres per day".
Mokonyane said her department's mandate to supply water knew no politics and she would not be drawn into petty political squabbles while the people and economy of the Western Cape were on the verge of disaster.
The World Wildlife Fund (WWF) on Wednesday called for Cape Town to introduce emergency bylaws for groundwater sharing when the city becomes the first in the world to run dry after water restrictions become insufficient amid a three-year drought.
Local authorities have warned four million people that if they do not reduce consumption by "day zero" - 12 April - they will have to queue at 200 standpipes for daily rations of 25 litres (6.6 U.S. gallons).
Trial water collection sites have already been set up, and in a further possible sign of things to come, people have been lining up with jerry cans at AB-Inbev's Newlands brewery to get up to 25 litres of free water from a mountain stream on its property.
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.
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.
According to The Guardian, Elliott's restaurant Cape to Cuba stopped serving tap water and is asking customers to only flush solids while using the restrooms.
Zille's spokesperson Michael Mpofu said the strategy plan included the deployment of forces at the various points of distribution across the metro, regular patrols, and the escorting of water resources to critical points where necessary.
The DA notes the statement released by Water and Sanitation Minister, Nomvula Mokonyane, following an earlier media briefing by DA Leader, Mmusi Maimane, detailing a programme of action to avert "Day Zero".