The swimming pools, well-watered gardens and clean cars of the rich are driving water crises in cities at least as much as the climate emergency or population growth, according to an analysis. The researchers said the vast difference in water use between rich and poor citizens had been largely overlooked in seeking solutions to water shortages, with the focus instead on attempts to increase supply and higher prices for water. They said the only way to protect water supplies was by redistributing water resources more equally. The study used Cape Town in South Africa as a case study and found the richest people used 50 times more water than the poorest. When the Day Zero water crisis struck the city in 2018, after several years of drought, the poorest were left without enough water for their basic needs, the scientists said. Cape Town was far from unique, the researchers said, with similar problems in many cities around the world. Since 2000, more than 80 big cities had experienced extreme drought and water shortages, they said, including Miami, Melbourne, London, Barcelona, São Paulo, Beijing, Bengaluru and Harare. The researchers said urban water crises were expected to become more frequent, with more than 1 billion city dwellers expected to experience water shortages in the near future. In March, a report by the Global Commission on the Economics of Water concluded that the world faces an imminent water crisis, with demand expected to outstrip supply by 40% by 2030. Prof Hannah Cloke, at the University of Reading, UK, and co-author of the new study, said: “Climate change and population growth mean that water is becoming a more precious resource in big cities, but we have shown that social inequality is the biggest problem for poorer people getting access to water for their everyday needs. “Our projections show this crisis could get worse as the gap between the rich and the poor widens in many parts of the world. Ultimately, everyone will suffer the consequences unless we develop fairer ways to share water in cities.” The study, published in the journal Nature Sustainability, used data to develop a model of city water use that took account of different income levels. In Cape Town, it found the richest group – 14% of the city’s population – used 51% of the water consumed in the city. In contrast, the poorest group – 62% of the population – used just 27% of the water. Most of the water used the richest group was for non-basic needs. The model, which could be applied to other cities, showed that changes in water use by the richest group had a bigger impact on overall water availability than changes in population or droughts related to the climate crisis. The researchers also said increased use of private boreholes in times of shortage by the richest citizens substantially depleted groundwater resources. The scientists said failing to account for social inequality in a water crisis often led to technocratic solutions that simply reproduced the uneven and unsustainable water use patterns that contributed to the water crisis in the first place. Prof Mariana Mazzucato, at University College London, UK, and a lead author of the report from the Global Commission on the Economics of Water, said: “We need a much more proactive, and ambitious, common good approach [to the water crisis]. We have to put justice and equity at the centre of this, it’s not just a technological or finance problem.” The new analysis quoted the conclusion of a 2016 report that said: “For most of the world, the era of cheap and plentiful drinking water has passed.” Cloke and her colleagues added: “It is time to agree about how society should share life’s most essential natural resource.”