Cape Town, South Africa has a few extra days to solve its water crisis before the taps shut down for four million residents.

The city just pushed Day Zero, the date when the water reserve dips below 13.5% capacity and the Cape Town government shuts off taps across the city, to May 11. Cape Town had initially set Day Zero for April 16 and then April 22 but shifted Day Zero again because they expect agricultural water use to decrease in March and April since many farmers have already used up their allotted water supply.

Take Action: Urge Governments And Businesses To Invest In Clean Water And Toilets

To avoid becoming the world’s first major city to run out of water, city officials and water conservation advocates say industries and individuals — especially wealthy residents filling up their swimming pools and watering their lawns — have to adjust their water use habits. Only about half of Capetonians have complied with the rationing rules, which mandate that residents use no more than 50 liters of water a day.

“Although many Capetonians are diligently saving water, there are many that are not,” Cape Town’s government “Think Water” website states. “Only if each of us reduces our daily use down to 50 litres or less, and the City implements the necessary projects, will we avoid Day Zero.”

Read More: Cape Town Is About to Run Out of Water

Years of severe drought have shrunk Cape Town’s water supply and forced residents to face the consequences of their water consumption. But water crises pose a daily struggle for roughly 2 billion people around the world, including more than 750 million people in sub-Saharan Africa, who lack access to clean water because of droughts, conflicts, and contamination.

Global Citizen campaigns on ensuring everyone has access to safe, clean water. You can take acton here.

If Day Zero arrives, the city will shut down the majority of individual taps and conserve water for absolutely essential uses, like hospitals. The city will then open 200 community taps and compel residents to line up to fill containers with no more than 25 liters of water per person.

Read More: Cape Town Isn't the Only African City Facing Water Shortages

The restrictions would force a major change in behavior for wealthier Capetonians, especially in the city suburbs where people often fail to consider the consequences of their water use.

“It has been in the areas where people have gardens, they have swimming pools and they are much more profligate in the way that they use water, because they’re used to the water just being, coming out of the taps,” Kirsty Carden of the Future Water Institute at the University of Cape Town told the Associated Press. “There have been problems in the more affluent areas where people are just, ‘We’ll pay for it.’”

But many of the region’s poorest residents live in ramshackle homes across sprawling townships designed to segregate black South Africans during Apartheid. Carden said 1 million of the city’s residents — the poorest citizens — account for just 4.5% of the city’s water consumption. In contrast, evaporation accounts for the 15% during the peak summer months, the city website states.

Poor Capetonians already depend on community taps to get their drinking water but now face even starker consumption choices.

“Before, I was using two kettles of water to wash myself,” township resident Vuyo Kazi told the AP. “So now I use one kettle of water.”