Imagine a world where rain isn't just a weather event, but a valuable resource. That's the reality in China, where they've transformed rainfall into an asset, especially in urban environments.
When the iconic Taiwanese rock band Mayday prepared to perform in Beijing's National Stadium (also known as the Bird's Nest) in May 2023, fans had reason to worry about the weather. But, as an official newsletter from China's Ministry of Water Resources reassured them, the stadium had a 'secret weapon'.
This secret weapon? A sophisticated network of tubes woven throughout the Bird's Nest's exterior, designed to capture rainfall. These tubes channel rainwater into underwater storage tanks, where it's filtered and prepared for reuse within the building. The result? At least 50% of the stadium's water needs are met by recycled rainwater – from flushing toilets to watering the lawns. The entire system can treat a staggering 58,000 tonnes of rainwater annually.
The Bird's Nest is just one shining example of China's dedication to 'urban rainwater harvesting' (URWH). Across the country, major buildings are being constructed with URWH in mind.
For instance, the National Aquatics Centre, located across from the Bird's Nest, boasts a rainwater harvesting system capable of collecting approximately 10,000 tonnes of rainwater each year, which is equivalent to the amount used by 100 households.
According to the Beijing local government, the city reuses 50 million cubic meters of rainwater annually. This, along with other sources, allows recycled water to meet over 30% of Beijing's water needs.
It's not just public infrastructure that's embracing URWH. In 2022, the drone company DJI unveiled its new headquarters in Shenzhen, featuring sky gardens and an integrated rainwater harvesting system to irrigate the lawns.
China's URWH efforts are closely tied to the 'sponge city' concept, an urban planning strategy rooted in ancient water systems. This concept, brought into the modern era by landscape architect Yu Kongjian, emphasizes the use of green spaces, wetlands, and permeable paving, alongside traditional drainage systems, to mitigate flood risks, especially in China's humid south.
But here's where it gets controversial... The concept of reusing rainwater is especially relevant in China's dry north, which struggles with seasonal droughts. Managing water flow has been a challenge for Chinese rulers for millennia. Historical records show that ponds were built as early as the Qin and Han dynasties to store rainwater.
'China has a special affinity for rainwater,' says Wang Dong, director general of the ecological city studio at Turenscape. Traditional Chinese homes were often built around a central courtyard, with rooftops designed to collect water, which symbolized wealth. This water was then directed into the home, signifying the accumulation of wealth.
Wang adds that 'Chinese people have long highly valued the utilisation of water resources, it is deeply embedded in our DNA.'
In 1995, China hosted its first modern-day national seminar on rainwater utilization in Lanzhou, a dry northern city. URWH began to be incorporated into official engineering codes in the following decades, with the 2008 Olympics serving as a showcase for these designs. As Yu’s “sponge city” concept gained popularity in the 2010s and was adopted as an official government strategy in 2014, URWH became a cornerstone of China’s national planning. The government now aims to reuse 70% of rainfall in sponge cities.
And this is the part most people miss... According to Chinese media reports, the URWH industry in China, including products like storage tanks and filtration systems, reached 126 billion yuan (£13.5 billion) in 2023, with further growth expected.
But, there's a catch! Reusing rainwater isn't as simple as collecting it. It requires designing buildings with a separate 'grey' water system to keep recycled water distinct from drinking water.
However, architects embrace this challenge. Dan Sibert, a senior partner at the architecture firm Foster and Partners, who has worked on several URWH projects in China, states that designs that absorb and reuse rainwater are 'absolutely fundamental to the development.'
He adds, 'For us as architects, what’s really exciting is how do you utilize the thing that could be a constraint to make the lives of the people in the buildings and around the buildings much better?'
Beyond environmental benefits, Sibert believes URWH enhances the experience of people using China’s modern buildings, making them feel like they are in an ecologically friendly space. 'If you’re flushing the toilet using grey water, it’s good that people know that,' he says.
So, what do you think? Could this be a model for other countries facing water scarcity? Do you see any potential drawbacks or challenges in implementing such systems? Share your thoughts in the comments!
