How the Built Environment Can Address the Global Water Crisis

Global | Wednesday, 14 August 2024
Reading Time : 8 minutes

By 2030, the World Green Building Council predicts a 40% gap between freshwater supply and demand globally. Already, 1 in 4 people don’t have access to safe, clean drinking water and that could rise to over half the world’s population by 2050.

The built environment has an important role to play in tackling the challenge and accelerating new opportunities. Buildings and construction are responsible for around 15% of freshwater use globally. As water availability declines and population growth and urbanization increase, they need to reduce demand and replenish groundwater supplies. We also need to strengthen the resilience of our cities and communities as climate-related extreme weather events increase.

Our experts are at the forefront of innovative projects around the world, helping to provide a blueprint for change.

Developing a circular economy for water

A circular economy approach encourages us to shift away from the linear route of ‘take, make, use and dispose’ and reset our minds to focus on reducing the amount of virgin resources we use and maintaining them in use at their highest value for as long as possible – providing a powerful approach for water management. Maree Marshall, Australian Lead for Waste Management & Circular Economy in our Melbourne office explains: “It starts at the master planning stage, where we can make an impact on a project at scale by embedding a circular design approach. For example, by using water-sensitive urban design and nature-based solutions to work with water, rather than against it. At a precinct and individual building level, we can design developments that are water efficient by capturing rainwater, reusing greywater from showers, and installing water efficiency fixtures and monitoring systems such as district metering to prevent waste.”

In New Zealand, our experts are developing sponge cities inspired by Indigenous communities that use blue-green infrastructure such as ponds and wetlands to absorb, store and slowly release stormwater back into the watershed. Protecting people, the environment and biodiversity.

Greywater delivers clear benefits

Toilet flushing accounts for around 30%-40% of water use in residential and commercial buildings so greywater systems are essential to reduce demand. However, education is still needed to share the benefits with developers and building users. Especially in parts of the world where water is perceived as cheap and plentiful and potable (drinkable) water is used for non-potable uses like flushing.

Chris Moore, Director at WSP in the UK believes more robust legislation will be a gamechanger. “New standards such as NABERS in Australia require buildings to monitor their operational water use, which will encourage developers to consider water efficiency at the design stage of a project. In some water-stressed parts of the UK such as Cambridge, water neutrality is already a requirement for planning permission.”

To scale up the benefits of greywater systems and meet demand in commercial buildings, the built environment needs to think at a precinct or community level says Helen Bali, Head of Water for the Middle East: “Our engineers in the Middle East have installed greywater treatment systems for toilet flushing in the basements of high-rise buildings across an entire district – significantly reducing freshwater demand. We’ve also designed an irrigation system for the area that removes brine from a deeper salty groundwater that would otherwise be wasted – enabling it to be used to water plants and trees.”

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Watershed in Seattle, USA. Image courtesy of Weber Thompson

Buildings can become water reuse systems in themselves

Beyond installing water reuse systems into new builds and retrofits, buildings themselves can do the same at scale. Zach Stevens, Vice President – Built Ecology in our Seattle office explains:

"Watershed is a smart building in the city that features a large, rooftop catchment and sculptural gutter system to capture rainwater and carry it to a 20,000-gallon cistern supplying non-potable water to water closets and irrigation systems. The result is a more than 85% reduction in potable water consumption. The site also includes bioretention planters and steel weirs to filter and treat up to 400,000 gallons of runoff from the adjacent Aurora Bridge, helping to reduce pollution in one of Seattle’s major lakes.”

Innovative solutions like this, supported by rainfall modelling, will help the built environment adapt to climate change as inconsistent rainfall makes it harder to design rainwater capture systems with a fixed capacity.

There are also nature-based solutions such as the Eco-Machine™ – a constructed wetland in a mechanical setting developed by our client at the Omega Center for Sustainable Living. Plants clean the center’s wastewater and return it to the aquifer it came from in a continuous loop, while the nutrients in the wastewater nourish the plants.

Not all water is visible

Calculating the water footprint of a project and how water flows through every stage is key to improving water efficiency. Water is used, directly and indirectly, to manufacture, transport and install building materials and provide services to building users and communities. From drinking water to air conditioning.

We work closely with our clients to help them understand the water impact of their projects and how it can be mitigated – through rigorous lifecycle analysis and environmental impact assessments.

To add to the challenge, the global building floor area is expected to increase 75% by 2050 – equivalent to adding the surface of the city of Paris every week. Reusing existing buildings, components and materials has never been more important and will save water as well as embodied carbon emissions.

Joined-up thinking is needed

Water storage, distribution and use accounts for 10% of global greenhouse gas emissions – so to reach carbon net zero, we need to think about water as well as energy. Renewable sources like wind and solar PV don’t take much water to produce, but others including biofuels, nuclear power and carbon capture, utilization and storage are more water intensive. The water-energy nexus is often complex. For example, producing hydrogen uses water, but hydrogen as an energy vector results in water emissions, returning it to the water cycle.

Overall, integrated water management is key to achieving cities’ multiple goals. Andrea Gysin, Head of Discipline, Water Strategic Asset Management in the UK explains: “More needs to be done at a national planning level to coordinate planning and optimize funding both within and across sectors. For instance, building hydrogen plants in drier areas where there is a demand needs to be carefully balanced against other infrastructure, particularly water and wastewater.

Water filtering and decontaminating - Copy

“At a regional and community level we are increasingly taking a more integrated approach; our experts work closely with different stakeholders that have a role in water stewardship, including local and national authorities and representatives from major water users such as industry and agriculture, to ensure that we are maximising the value of investments in water management for all stakeholders.

“For example, we’re currently working on a 20-year flood risk management and action plan with the Somerset Rivers Authority (SRA) – a unique organization that brings together risk management authorities and non-governmental organizations. Because the SRA is funded through the local council tax, it was particularly important that the revised plan reflects the priorities of Somerset residents. The plan demonstrates how it meets the SRA’s agreed objectives and sets out the predicted costs, funding mechanisms and delivery partners. This opens a pathway for a new strategy for Somerset, enabling the county to strengthen its future flood resilience and adaptation.”

Necessity is the mother of invention

Less than 1% of the earth’s water is naturally available for human consumption – it has to be managed. However, much of the world’s water and wastewater infrastructure was built for a different climate scenario and is impacted by under-investment as well as increased demand. Risk needs to be split between different water sources and efficiency prioritized for a more secure, resilient water supply.

Countries on the frontline of the water crisis are pioneering solutions that could be scaled up. For example, a project in a Sub-Saharan African city impacted by drought aims to meet 50% of the population’s potable water demand from recycled municipal wastewater in the next few years. The water reclamation plant, which is already supplying 25% of the city’s drinking water, uses a 10-step purification process to remove contaminants and blends purified water with water from natural sources. Nothing is wasted as the plant is powered by sewage sludge – a byproduct of the wastewater treatment process.

Patrick Riley, Director: Water and Maritime in our Cape Town office is clear: “Engineering innovations are vital to help cities diversify their water supplies, reduce demand and support user reduction programmes without putting an unfair burden on communities. Looking at water through an environmental justice lens is vital to get the balance right – between reducing water use and protecting people’s right to clean, affordable water.”

Martin Sing, Market Lead – Energy & Sustainability in Canada concludes: “It’s important to recognize that water is the world’s most precious resource. We need to work together and find better solutions to protect it.”

Find out more in the World Green Building Council’s latest publication ‘Building a water resilient future for everyone, everywhere’ – supported by WSP as a Global Programme Partner for WGBC’s Circularity Accelerator.