On April 12, 2018, the four million residents of Cape Town—a city with some of the widest socioeconomic disparities between residents on the African continent—narrowly avoided a major shortage of drinking water.

A rising population and climate change set off the “largest drought-induced municipal water failure in modern history,” according to Bloomberg News. South African leaders had warned of "Day Zero," on which the city would be forced to shut off homes’ and businesses’ water because of low levels in reservoirs.

Helen Zille, Cape Town’s mayor from 2006 to 2009 and the Premier of South Africa’s Western Cape Province during this crisis, warned of the chaos that could erupt from such a severe water shortage. "The question that dominates my waking hours now is: When Day Zero arrives, how do we make water accessible and prevent anarchy?" she said in a guest newspaper column published in January 2018.

For wealthier Capetonians, Day Zero meant facing conditions that those in the city’s less wealthy, majority Black townships have lived with for years. There, people practice conserving water as a precious resource, commonly drawing water from communal taps. These township residents make up half the population, yet they consume only 5% of the city’s water. This divide stems from centuries of racial segregation followed by a period of strict, legally enforced segregation, known as apartheid. Racial tensions and segregation have existed in South Africa since the Dutch began settling the land, which was already governed and occupied by Indigenous chiefdoms, in the 1650s. But in 1948, South Africa’s all White government formally instituted apartheid, which removed Black South Africans from their homes, forcing them to relocate to areas or townships according to their ethnicity. Well-resourced towns and cities and well-paying jobs were reserved for White South Africans. While activism from Black leaders and supporters paved the way for the end of these laws and the creation of a new government in 1994, the harmful legacy of racial segregation persists.

While Day Zero conditions were an everyday reality for some residents, before this water crisis, few leaders had thought that a water shutdown across a large, affluent city might be necessary. But across the world, from North America to South America and from Australia to Asia, development of natural lands, rising populations and climate change have been threatening the freshwater supply in cities.

The Path to “Day Zero”

In the lead up to Day Zero, National Geographic reported that the situation seemed to worsen each day. The city prepared 200 emergency water stations outside grocery stores and neighborhood gathering spots, with each serving almost 20,000 residents. Cape Town officials worked with the military to store emergency water on their bases. They also banned filling swimming pools and washing cars. Authorities set up water-theft patrols at natural springs to prevent fights over water. Authorities also received reports of traders who increased prices of bottled water to profit from the crisis.

While the city encouraged lower water consumption among residents, most ignored those requests. In January 2018, the city requested steeper reductions, asking residents to consume just 50 liters (13 gallons) per day. Failure to heed this warning would force the entire city into Day Zero, officials warned, where all residents would have to use 25 liters (6.6 gallons) or less per day.

For wealthy, White Capetonians, the crisis meant challenging their fundamental attitudes about overconsumption. But Black Capetonians living in townships have a different lived experience. “For us, it’s a shame for the city to say it’s a water crisis because most of us—especially in the Black townships—we get a lot of people that must fetch water,” Zama Timbela with the Alternative Information and Development Centre told National Geographic. “[They] have been living in Day Zero for many years.”

Climate and Water

The idea that Cape Town could run out of water was not a new one. South Africa is largely arid, but Cape Town boasts a Mediterranean climate. Breezes blow in off Cape Town's warm coastal waters where they meet Table Mountain. The mountain traps the moist, warm air, which creates rains that fill the area’s freshwater sources. But in the 20 years leading up to the Day Zero crisis, officials and advocates recognized that fresh water was a finite resource. They were also aware of the unequal access to water between townships and the rest of the city. Cape Town made progress in reducing water usage and leaks. The city even won international water management awards.

But climate change from large amounts of heat-trapping carbon dioxide and other greenhouse gases has altered weather patterns rapidly around the globe. While greenhouse gases naturally exist in the atmosphere, human activities, like burning fossil fuels and cutting down forests, have emitted massive amounts of these gases. City officials knew that population growth and the projected drier, hotter weather, with less winter rainfall due to climate change, would require stronger water-management strategies.

The lead up to Day Zero was three years of the worst drought in over a hundred years. In 2014, Cape Town’s six reservoirs were full, but the drought quickly changed that. According to NASA data, in January of 2018, reservoirs stood at 26 percent of capacity. City officials planned to cut the taps when levels dropped to 13.5 percent.

Crisis Averted?

Day Zero’s initial April date was pushed to May and then indefinitely, thanks in part to the severe measures taken. Cape Town’s dramatic action successfully reduced its water demand by 30%. These measures largely included efforts to curb the middle class’ water usage by shutting down some public taps, reducing the water flow to residences and installing water management devices for high-volume users. Ultimately, the hope is that Cape Town’s residents have become more aware of their water use and continue their adoption of water-saving habits.

During the crisis, the city also implemented ways to capture new sources of water, including desalination of seawater. However, desalination proved expensive and has caused concern regarding environmental impacts. Notably, the desalination plants were only a temporary measure.

In some ways, averting Day Zero was a stroke of luck. The rains eventually returned and helped the city avoid the worst of the crisis.

Cape Town has avoided Day Zero for now, but the threat continues to loom over much of the city. Poorer neighborhoods are the most impacted by water scarcity and the climate crisis. Even in urban areas, water-saving measures are still implemented, though they are less strict. All the while, demand for water in the area continues to increase.

Water Around the World

Similar water crises have affected cities around the world. In Mexico City, home to more than 23 million people, many have running water for only part of the day. A fifth of residents can access running water from their taps for just a few hours each week. In 2024, the city narrowly avoided its own Day Zero. Some of India’s largest cities also struggle with water access. Chennai, a city of 11 million, came close to experiencing its own Day Zero in 2019 despite being one of the rainiest cities in the world.

In greater Jakarta, Indonesia, many of the 30 million residents lack piped water and have resorted to digging unregulated wells, pumping water from the ground. As a result, the city is sinking and groundwater supply is dwindling. Poor sanitation—worsened by increased flooding from climate change—also threatens the greater Jakarta water supply. United Nations agencies are working with Indonesia’s government to improve water management and sanitation. The government is also building new reservoirs.

Similar to Cape Town's crisis, in 2015, reservoirs in São Paulo, Brazil, dropped low enough that pipes drew in mud. And like Mexico City, officials cut water in many homes to a few hours twice a week. Fortunately, rains prevented Brazilian authorities from having to cut off water altogether. Now, catastrophic floods from La Niña pose a new threat.

Competition for water is increasing around the world. Growing populations, agriculture and increasing affluence all demand more water usage. This competition drives inequitable access to water, with wealthier and more powerful governing organizations controlling the supply.

As in Jakarta, climate change is causing more intense storms and droughts in countries around the world. This especially strains regions with inadequate infrastructure. Addressing climate change by preventing further emissions and improving water management strategies are critical steps in avoiding Day Zero everywhere.