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Rich people use so much water that it is threatening the global supply

The disproportionate amount of water used by the richest in society must be cut down to ensure future demand can be met, researchers have argued.

Water demand is rising at an alarming rate across the world, particularly in urban areas, says Elisa Savelli at Uppsala University, Sweden.

According to a United Nations report, 2.4 billion people worldwide living in cities could face water shortages in 2050, up from 933 million people in 2016. The escalating problem is due to a range of factors, including climate change and growing urban populations.

Severe water shortages are already playing out in some countries. In Cape Town, South Africa, a drought between 2015 and 2018 led to reservoir levels in the city falling to just 12.3 per cent of their usual levels. People were told to limit their water use to avoid a day when the city’s supply would run out, widely referred to as “Day Zero”.

One little-studied issue is how demand for water is affected by its uneven use by different segments of society, says Savelli. To learn more, she and her colleagues modelled water use by Cape Town’s different socio-economic groups before and during its drought. The groups were based on the city’s 2020 census, which classed 1.4 per cent of the population as elites, 12.3 per cent as upper-middle income, 24.8 per cent as lower-middle income, 40.5 per cent as lower income and 21 per cent as informal dwellers.

The researchers then modelled water use for the five groups according to information they collected on average household usage through interviews and focus groups.

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Prior to the drought, those in the elite and upper-middle income groups accounted for an estimated 51 per cent of the city’s water use, despite making up only 13.7 per cent of the population. In comparison, the lower income and informal dwellers – 61.5 per cent of the city’s population – were found to use just 27 per cent of the city’s water.

Savelli says there are several reasons why the richest in Cape Town use so much water. “Many people have swimming pools, which need a lot of water,” she says. “They also have flashy gardens, which need to be regularly irrigated.”

Similar patterns probably occur in other hot cities with high levels of inequality, such as Barcelona in Spain, São Paulo in Brazil and Chennai in India, says Savelli.

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During Cape Town’s drought, the team found that all the socio-economic groups reduced their water use, but those with the lowest incomes were more likely to struggle to access water for their basic needs, such as cooking, compared with those with the highest incomes.

The richer groups were more likely to have access to private sources of water, such as bottled water and private wells, too. Excessive use of these wells can deplete local aquifers – underground layers of water-bearing rocks that transmit water to springs – which could exacerbate future droughts, says Savelli.

The modelling also found that if climate change increases Cape Town’s average temperature by 2°C, it could lead to even greater use of private wells by the richest in society.

Based on these results, policy-makers should no longer just analyse water use across a city’s entire population, says Savelli. They should also avoid blanket water-rationing rules that may disproportionately affect the most vulnerable people, she says.

Unfortunately, there are probably no straightforward fixes to uneven water use in cities. “To a certain extent, to solve this issue, we need to criticise and contest the political and economic systems that regulate all our lives,” she says.

Overconsumption of water by higher-income groups is unsustainable for global water supplies and needs to be cut down, says Savelli.

“For too long, we have thought about water security in terms of water availability or infrastructure, but these analyses get at more granular disparities about reliability and use,” says Sera Young at Northwestern University, Illinois.

“It’s clear we cannot simply rely on increased water supply for our thirsty lifestyles,” she says. “Climate change, crumbling infrastructure, such as leaking sewage pipes, and growing urban populations mean that water security will only be increasingly challenged.”

Journal reference:

Nature Sustainability DOI: 10.1038/s41893-023-01100-0

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