The unsustainable consumption of the rich — including the use of swimming pools, garden irrigation and washing cars — is a key driver of urban water crises, according to a new study that calls for a fresh approach to tackling the issue.

Published in the Nature Sustainability journal this week, the peer-reviewed research looked at the South African city of Cape Town, which has experienced severe drought in recent years.

For the study, researchers split Cape Town’s urban population into five social groupings and then modeled water consumption.

“Despite representing only 1.4% and 12.3% of the total population, respectively, elite and upper-middle-income groups together use more than half (51%) of the water consumed by the entire city,” they said.

“Informal dwellers and lower-income households constitute together 61.5% of Cape Town’s population but consume a mere 27.3% of the city’s water.”

The consequences of such an imbalance are severe, according to the analysis.

“Overall, these results support the argument that domestic water consumption in unequal urban areas such as Cape Town is likely to become unsustainable as a result of excessive consumption among privileged social groups,” it said.

“Specifically, privileged water consumption is unsustainable because in the short term, it disproportionally uses the water available for the entire urban population.”

Longer term, the report described what it called privileged consumption as constituting an environmental threat to the status of local water sources.

The report’s abstract said Cape Town, with its “highly unequal metropolitan area,” served “as a case in point to illustrate how unsustainable water use by the elite can exacerbate urban water crises at least as much as climate change or population growth.”

The study, which was led by Elisa Savelli at Uppsala University in Sweden, proposes a new approach to preserving water resources centered around “altering privileged lifestyles, limiting water use for amenities and redistributing income and water resources more equally.”

The research comes as access to water continues to dominate headlines. According to the United Nations, 2 billion people did not have access to safely managed drinking water services in 2020.

Hannah Cloke is a hydrologist at the University of Reading in the U.K. and was a co-author of the study.

“We have shown that social inequality is the biggest problem for poorer people getting access to water for their everyday needs,” she said in a statement.

Over 80 major cities across the world have been hit by water shortages over recent decades, she said, adding that the study highlighted how the crisis “could get worse still as the gap between the rich and the poor widens in many parts of the world.”

“This shows the close links between social, economic and environmental inequality. Ultimately, everyone will suffer the consequences unless we develop fairer ways to share water in cities,” she added.