Emergency steps to slash water consumption have given a reprieve to Cape Town, allowing the city to postpone its much-feared "Day Zero" – the day when it would become the world's first major city to cut off the entire supply of water to its homes.

The expected date of Day Zero, previously set for April 16, has now been pushed back to May 11, according to an announcement by the city government on Monday. If the city can delay this date further, to the end of June, it might be saved by seasonal rains that normally occur in the South African winter.

"I am confident we can beat this," Cape Town deputy mayor Ian Neilson told The Globe and Mail in an interview on Monday. "Everything is heading in the right direction. It's a great relief to us."

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But even as Cape Town heard the good news of the deferred deadline, other regions of South Africa were witnessing threats to their water supply as a long-term drought continued. In the Eastern Cape province, some towns are rationing water, while other provinces are carefully watching their supplies.

Cape Town has told each of its residents to limit themselves to 50 litres of water per day. That amount is just one-fifth of the water used by the average Canadian each day.

If Day Zero arrives, the city's residents would have to queue up to collect their water from shared taps at collection points, where they would be limited to just 25 litres a day. The city admits this would be disastrous. It says it would have to deploy the army and police to provide security at the collection points, where fights could erupt.

Meanwhile, the city is assuring tourists and business visitors that they can still come to Cape Town, despite the water rationing. The city, nestled between the Atlantic Ocean and a spectacular mountain ridge, is a major tourist attraction and the second biggest city in South Africa, with nearly four million residents.

The delay in Day Zero, announced on Monday, is largely due to a reduction in agricultural use of the water dams that supply Cape Town. The national government has now shut off the supply of water from the dams to two irrigation boards, after they completed their use of their allocated share. In previous years, farmers were able to use more than their allocated share, but this won't happen this year, officials say.

They admit that farmers could be hurt by the reduction. "Certainly we are concerned that the reduction of irrigation water will lead to lower crops and higher prices," Mr. Neilson said.

"And probably the biggest impact will be the impact on job availability. But every single business uses water to some extent, so reducing supply potentially has consequences."

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Analysts note that the farms around Cape Town are mostly fruit and wine producers. They don't have a big impact on food inflation in South Africa, but they produce huge export earnings and create thousands of jobs.

To cut water consumption, Cape Town is taking drastic steps to throttle the water pressure in its pipes. Many residents are getting only a trickle of water in their taps in the daytime. Some, especially at the top of high-rise buildings, are sometimes getting no water at all.

The city is also installing thousands of devices to allow it to regulate the water flow to what it calls "delinquent" households – those who continue to use large amounts of water.

The latest estimates show that the city's residents and businesses are now consuming 547 million litres of water per day. This is about 70 million litres lower than the amount last month, but still about 100 million litres above the target.

"This is a welcome decline in water usage and gives Cape Town and some of the other municipalities hope, but importantly we need to get our consumption down to 450 million litres per day to prevent the remaining water supplies running out before the arrival of water rains," the city government said in a statement on Monday.

"Last year, we had abnormally low winter rainfall, and we cannot assume that this year will be any different," the statement said. "Even if we have been given a slight reprieve at this stage, we are likely to be facing a late and dry winter. All preparations for the possibility of reaching Day Zero continue in earnest."

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Mmusi Maimane, leader of the Democratic Alliance party that governs Cape Town, said the latest delay in Day Zero is proof that the threat can be defeated.

"This significant victory is thanks in large part to the continued heroic water-saving efforts of the residents and businesses of Cape Town, as well as a sharp reduction of agricultural drawdowns," he said.