The immense challenge of the province's longest drought on record will test the capabilities at all levels of government to their limits, Western Cape Premier Helen Zille said during her state-of-the-province address on Thursday.

Addressing the provincial parliament, Zille said: "While addressing a provincial state of disaster, declared in May 2017, we also had to continue delivering on our core constitutional mandates. This is not a normal drought. Hydrologists analysing rainfall records as far back as they go have calculated that a severe three-year drought in the Western Cape has a 25% chance of occurring."

The devastating drought which has affected Cape Town and other areas of the Western Cape has led to the implementation of severe water restrictions and the possibility of Day Zero when the city's taps run dry.

In February, the City of Cape Town implemented Level 6B restrictions, limiting residents to 50 litres of water per person per day.

The City of Cape Town on Tuesday announced that water saving efforts by residents had led to Day Zero being further moved to July 9 from June 4.

On Wednesday, finance minister Malusi Gigaba announced in his budget speech that R6-billion has been set aside for drought relief in the Western Cape and other parts of South Africa.

However, Zille slammed the national department of water and sanitation, saying that to date no national funding had been made available for augmentation in the Western Cape water crisis.

"As a result, the City of Cape Town has stepped into the breach with aquifer extraction, water reuse and desalination projects to the tune of some R5.9-billion over the five-year medium term revenue expenditure framework," she said, adding that no local government should have to shoulder the burden of capital and operational costs for what was a national function.

"I note that in yesterday's budget, R6-billion was set aside for drought relief and infrastructure for the five provinces hit by the current drought."

Zille, though, said that although R6-billion is a lot of money, "divided between five provinces it will hardly touch sides if it is intended both for relief and new infrastructure".

"The city's infrastructure build programme on its own amounts to almost R6-billion."