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Why we need to think of our cities as giant water collection facilities

  • Why we need to think of our cities as giant water collection facilities

About the blog

Geertjo van Dijk
Global Product Manager - Storm Water Management at Wavin Group.
Schneider Electric

Like pandemics of the past, the COVID-19 pandemic has taught us many lessons on how we can improve urban life. Among other takeaways, it has reinforced how connected our world has become and how critical it is to consider our interdependence when making all kinds of decisions, from public health to the environment.

COVID has also underlined the value of often-overlooked concepts like resilience and circularity as supply chains have been disrupted and scarcity has overtaken abundance as the prevailing condition in several aspects of urban life. Our current urban paradigm is highly dependent on fragile large-scale systems prone to destabilization from unpredictable events like pandemics. COVID makes it clear that we need to reorganize cities around a more local and circular way of life with resilience and sustainability at the core. This is most important when it comes to the most essential aspect of civilization: water.

The way we treat water today is unsustainable and inefficient. As soon as it enters our cities, whether that is as surface water, groundwater, or rainwater, we try to get rid of it. We treat water linearly - source to use to disposal - instead of circularly, presenting a great opportunity to future-proof cities and make them more livable for centuries to come.

Despite long- and short-term shortages, the conventional approach of designing centralized urban utility systems has been driven by 19th century technological principles, applied during a time of abundant resource supply and relatively smaller demand. When water is plentiful, this tradeoff is feasible. In a more densely populated world ravaged by climate change, this tradeoff has flipped.

COVID makes it clear that we need to reorganize cities around a more local and circular way of life with resilience and sustainability at the core

Linear water management was barely viable in a world of excess supply. Today, as urban populations and economies grow, it is highly impractical. Cities face five major environmental obstacles in particular as they look to reliably provide clean drinking water to residents: flooding, drought, groundwater depletion, surface level pollution, and heat stress. Thanks to these challenges and others, the global urban population facing water scarcity is expected to rise from just under one billion people in 2016 to about two billion people in 2050.

Water scarcity affects the health and wellbeing of city residents along with environmental quality and socioeconomic development among other key factors that cities must balance in a warming world. As such, we must think differently about urban water management, keeping the present and the future in mind. Instead of seeing each system involved in the urban water cycle as separate and independent, we can connect those systems and manage them locally. From wastewater to rainwater to tap water, we can create circular and controlled water cycles around buildings, neighborhoods, and even cities.

Circularity means water is reused rather than used once and never more. At its core, circularity mimics nature, where everything is reused and nothing is wasted. A zero waste mentality would go a long way toward alleviating the global water crisis and many of the other major 21st century environmental challenges.

In this vein, we must see our cities as giant water collection facilities. As precipitation falls more erratically, cities must be prepared to capture water when and where it falls - for instance, on roofs and streets to avoid expensive transportation of clean water from elsewhere.

Managing water locally - and making every drop count - will only become more important as climate change destabilizes water supplies. Urban development requires more water per capita as melting glaciers and changing agricultural patterns make water more scarce. We need novel ways to future-proof water management, and an emphasis on decentralized water management - which disperses water closer to its source and minimizes surface discharges - allows for more flexibility and less waste. It reduces infrastructure costs, enhances resilience, and helps both humans and the environment.

With decentralization, water can be cleaned or filtered if needed and stored for the rainy days that are becoming both rarer and more intense. Stored water can be reused to water local vegetation - which cools and cleans the air among other notable benefits - or cool cities during hot and dry periods. Heavy rainfall can be slowly infiltrated back into the ground to replenish groundwater rather than cause flooding on prevalent concrete and asphalt surfaces without being used even once.

From wastewater to rainwater to tap water, we can create circular and controlled water cycles around buildings, neighborhoods, and even cities

Innovative technologies allow for smart urban water management that is both proactive and reactive, predicting how much rain is forecast to fall and then directing water to its most optimal use once it has fallen. Collected water can be reused - for instance, to irrigate community gardens or for residential or commercial building sanitation - or returned to the soil depending on what’s needed and how much water is forecasted to be available.

Furthermore, innovation and forward thinking can fully unlock the immense potential of circular local water management. Various water management solutions reliant on more dynamic and flexible water networks can both cut waste and enhance self-sufficiency. Warm wastewater from commercial or industrial activity (like data centers) can be used for heating and energy needs. Wastewater treatment plants can make biogas and thereby generate electricity. Wastewater can also be leveraged to generate fertilizer or organic matter that can support farming. And cities can foster market-based solutions that allow for wastewater to be bought, sold, or shared.     

Copenhagen, for instance, has implemented local water management largely in response to heavier rainfalls and rising sea levels. The city is building Cloudbursts, green and biodiverse sites sprinkled throughout the area that serve as vibrant recreational spaces in dry weather and water collectors in wet weather. Rainwater gathered from storms can then be stored elsewhere or siphoned out of the city. Copenhagen envisions hundreds of Cloudbursts to prepare for a warmer future. The Danish capital is just one of many global cities at the vanguard of local water management.

COVID has underscored that when it comes to essential goods and services, the modern world is racked with inequity and waste. In regards to urban water management, much of this stems from an outdated view of water that is impractical in the 21st century. As cities progressively become civilization’s principal organizing entities, with the greatest power to shape opportunities and outcomes for billions of people around the world, they must ensure their residents have clean, readily available water whether it’s wet or dry.

The key to turning this vision into a reality is to build local, circular water networks that prioritize sustainability and resilience. This will ensure that in spite of increasingly difficult societal circumstances, from pandemics to extreme weather events, clean water will always be reliably available to every city resident around the world. 

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