Imperial College London

Water 'Day Zero': What the world can learn from droughts in Cape Town

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Cities need a long-term strategy for water management, say academics from Imperial College London and the University of Cape Town.

In 2018, following several years of low rainfall and a particularly severe drought in South Africa, Cape Town, which is home to 4 million people, risked becoming the first major city in the modern era to run out of water – a critical juncture termed 'Day Zero'.

In a new briefing paper published by Imperial’s Grantham Institute – Climate Change and the Environment, academics from Imperial and the University of Cape Town consider the experiences of Cape Town and offer policy recommendations for how cities across the world can ensure long-term water security in years to come.   

Day Zero would happen in Cape Town when freshwater reservoir levels supplying the city fell below 13.5% of capacity, and would result in the majority of the city’s water network being shut off. 

Water is treated as an infinite resource, but it only takes two or three dry seasons to trigger a catastrophic drought. Robbie Parks Briefing co-author

In response, the City of Cape Town Municipal Government took drastic action, introducing a variety of measures to manage water demand and supply – and Day Zero was narrowly averted in 2018. Yet, as the climate changes, water shortages will become more common in cities around the world, making the experiences of Cape Town relevant to many urban areas. 

“Changing shifts in rain patterns are a major cause of water shortages and, as the climate changes, droughts and heatwaves will be more likely,” explains Robbie Parks, Research Postgraduate and briefing co-author. “Water is treated as an infinite resource, but it only takes two or three dry seasons to trigger a catastrophic drought – Cape Town is a prime example of that – so there needs to be a huge change in how water is managed.” 

The briefing describes the conditions that led to the drought in Cape Town, the social and economic impacts of the crisis, and the interventions that were implemented to respond to it. These measures included placing increasingly severe restrictions on how much water could be used, reducing water pressure across the city and installing Water Management Devices to minimise the amount of water used in homes, alongside an extensive public awareness campaign to encourage people to save water. 

“There are two scales of change,” says Robbie, “a permanent shift in personal attitudes about water use, and government-led policy driving long-term change to water management.”  

Megan McLaren, co-author and a Master's student from the University of Cape Town, believes the lasting impact on the Capetonians has been a new appreciation of the value of water, and of how wasteful of water people had been in the past.     

“Unless you work in the water sector (or have lived through water shortages), it is extremely easy to overlook and take for granted the incredible feat of science and nature that is involved in getting water to and from a city, and how vital it is for the functioning of modern life,” she says. “Making changes to this complex infrastructure requires a long-term view and a great degree of inter-disciplinary engagement to ensure that all aspects of the system are taken into account.”    

There needs to be more engagement and interaction between research institutions, governments and the public. Professor Ulrike Rivett Briefing co-author

Co-author Professor Ulrike Rivett says the drought in South Africa has shown that there needs to be more engagement and interaction between research institutions, governments and the public. “Such engagement has to move beyond the theoretical and often academic navel-gazing to constructive collaborations to find new ways of solving a crisis that affects all countries, not only South Africa,” she says. “We are hoping that through this briefing and our reflections we contribute to such engagement.” 

The briefing paper, Experiences and lessons in managing water from Cape Town, authored by Robbie ParksMegan McLarenProfessor Ralf Toumi and Professor Ulrike Rivett, is available to download on the Grantham Institute website

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Miss Lottie Butler

Miss Lottie Butler
The Grantham Institute for Climate Change

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