Over the last four decades, global water use has increased by about 1 percent per year. This rise is driven by many factors, including population growth, changing consumption patterns, and socioeconomic development. By 2050, the United Nations Water estimates urban water demand to increase by 80 percent. As freshwater needs continue to rise in cities, the sustainable management of urban water supply becomes even more critical.
In the past two decades, over 80 metropolitan cities around the world have experienced water shortages and extreme drought. Such urban water crises are expected to occur more frequently in the near future, therefore it’s crucial to understand how they unfold, who is vulnerable to them, and how they can be addressed.
Why urban water crises occur today
Many factors contribute to the development of today’s water crises, including changing land cover and use, urban infrastructure maintenance, and climate change, says Adriana Zuniga-Teran, neighborhood design and environmental sciences expert and assistant professor of geography, development, and environment at the University of Arizona.
For instance, impervious surfaces like concrete and asphalt often replace natural porous land cover as cities grow, resulting in less precipitation infiltration, which can affect the whole hydrological cycle. In addition, cities, farms, mines, and industrial land use all consume a lot of water compared to natural landscapes. Furthermore, rich and poor countries alike face issues with aging water infrastructure, which requires a massive amount of resources to upgrade. Lastly, climate change factors in because extreme weather events can make water more polluted, scarce, and/or unpredictable.
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In general, Zuniga-Teran says the reasons for urban water crises are, to an extent, caused by “a consequence of uncontrolled urban growth and the unsustainable use of water resources.”
Population growth is not enough to indicate water demand, because certain individuals and social groups use a lot of water (and other resources) while other groups don’t. What’s at play is the current political-economic system that makes it possible for some individuals to over consume water while others don’t even have access to it, says Elisa Savelli, a research fellow at the Uppsala University Department of Earth Sciences in Sweden.
Socioeconomic inequalities can drive water crises
According to a recent Nature Sustainability study on the metropolitan area of Cape Town, stark socioeconomic inequalities play a major role in the production of water crises. The authors built a model to account for unequal water consumption across different social groups, which allowed them to retrace who over consume water and who doesn’t. They found that privileged households with better access and financial resources are able to consume more water to use however they want to.
“We found that whilst constituting only 13 percent of the urban population, the elite consumed more than half of the city’s water, and for non-basic needs such as gardening or swimming pools,” says Savelli, who was lead author of the Nature study.
Not only did wealthier households consume more public water sources, but they also had access to private sources that aren’t controlled by municipalities, like boreholes. In comparison, informal dwellers and lower-income households constitute over 60 percent of the city population but consume only about 27 percent of the city’s water.
“Socioeconomic inequalities can drive water shortages and crises as much as, if not more than, population growth or climate change,” says Savelli. The current political-economic system triggers the unsustainable exploitation of water sources with the objective of accumulating profit and capital, without accounting for water as a common resource, she adds.
Wealthy people generally have the infrastructure to make water available to them, so it’s easier for them to consume it. They also have larger properties to maintain, larger dwelling units, pools, and more, says Stephanie Pincetl, director of the California Center for Sustainable Communities at UCLA.
“In places like the Southwest, we need to aggressively change outdoor landscapes,” says Pincetl. In California, landscape irrigation accounts for about 50 percent of annual residential water consumption. Overall, federal and local governments have a responsibility to manage urban water supplies sustainably and equitably.
Various strategies to manage urban water supply sustainably
To ensure more sustainable management of urban water supply, Pincetl suggests establishing tiered water rates where rates are higher with more consumption. Water use budgets per household are already in some places across the country, like Orange County, California. Those who stay within their monthly water budget get a lower rate per centum cubic feet (CCF) compared to those who go over it.
A 2021 Water Economics and Policy study looked into the county’s application of tiered rates and found that water was saved for the two agencies that converted to a budget-based rate structure at multiple levels of consumption. However, Zuniga-Teran says water demand policies that aim to control human behavior might not be enough to influence the behavior of wealthy residents. After all, they may not mind paying a lot more for water.
Municipalities can also acquire water rights by buying farmlands to change the water use from agricultural to municipal, says Zuniga-Teran. Back in the 1970s, Tucson, Arizona purchased over 20,000 acres of farmland in Avra Valley to acquire water rights and preserve groundwater. Investing in education and communication programs to help individuals learn how they can contribute to sustainable water management is also important, she adds. A 2022 Sustainability study in Mexico aimed to implement an environmental education program on water conservation in 10-year-old students. The authors found that such environmental programs can improve water use and conservation.
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A major part of sustainable resource utilization is water reuse for both potable and non-potable purposes. For instance, Zuniga-Teran says households can collect greywater—excess runoff water from showers or washing machines—and harvest rainwater to use for car washing or toilet flushing. Cities could also reuse reclaimed water, or treated municipal wastewater, and send it to a drinking water treatment plant to be directed into the drinking water distribution system. Meanwhile, stormwater, or surface water from heavy rain or snow, may be used to irrigate landscapes and replenish local aquifers while reducing flooding, she adds. All these alternative water sources could be treated and used for a variety of purposes.
“Instead of building another dam or promoting water technologies, policies should seek to alter privileged lifestyles, limit water use for amenities, and redistribute income and water resources more equally,” says Savelli. “The construction of additional infrastructure would not address the root cause of water overconsumption, and in turn, this and other technocratic solutions would protract current water crises into the future.”
When it comes to sustainable urban water management, cities should prioritize low-income, marginalized communities that still experience legacies of redlining and disinvestment and are likely to suffer the impacts of climate change the most, says Zuniga-Teran. Therefore, funding engagement efforts is critical as well. “Equity has to be at the forefront of all water-related efforts,” she adds. “To address inequities, community engagement is needed to make sure all voices are heard and that programs and policies are designed to address their particular needs.”
