Imagine flushing a toilet with rainwater – sounds futuristic, right? But in China, it's becoming a reality, and it's all part of a massive effort to turn rain into a valuable resource. You might think of rain as a nuisance, especially when it threatens outdoor events. Take, for instance, the time when Taiwanese rock band Mayday was scheduled to perform in Beijing's iconic National Stadium, affectionately known as the Bird's Nest. Fans worried the rain would ruin the show.
But here's the thing: the Bird's Nest has a secret weapon. An article published by China’s ministry of water resources reassured fans that the stadium is equipped with a sophisticated system of capillary-like tubes woven throughout its steel lattice. These tubes act like tiny straws, siphoning rainwater away from the structure. The water is then channeled into underground storage tanks, filtered, and recycled for use within the stadium. This ingenious system can meet at least 50% of the stadium's water needs, from flushing toilets and washing running tracks to irrigating the lawns. In total, the water system surrounding the Bird’s Nest can treat 58,000 tonnes of rainwater each year.
The Bird's Nest is just one example of China's commitment to "urban rainwater harvesting" (URWH). Across the country, major buildings are designed with URWH in mind. Right across from the Bird's Nest, the National Aquatics Centre boasts its own rainwater harvesting system, capable of collecting approximately 10,000 tonnes of rainwater annually – enough to supply 100 households. Beijing reuses 50 million cubic meters of rainwater each year, and together with sources like bathroom runoff, over 30% of the city's water needs are met through reused water.
And it's not just public buildings. Even drone maker DJI's Shenzhen headquarters features sky gardens and an integrated rainwater harvesting system to irrigate its lawns.
China's URWH efforts are closely tied to the "sponge city" concept, a modern urban planning strategy based on ancient water management techniques, revitalized by landscape architect Yu Kongjian. Sponge cities use green spaces, wetlands, and permeable paving to mitigate flood risks, particularly important in China's humid south.
But the concept of reusing captured rainwater is especially crucial in the drier northern regions of China, which are prone to seasonal droughts. For millennia, Chinese rulers have grappled with managing water resources. Records show that as early as the Qin and Han dynasties, ponds were constructed to store rainwater for domestic use.
“China has a special affinity for rainwater,” says Wang Dong, the director general of the ecological city studio at Turenscape. He explains that in traditional Chinese homes, rooftops were designed to collect rainwater, symbolizing wealth, and channel it into the home's interior.
The Chinese Communist Party (CCP) recognized the importance of URWH early on. In 1995, they hosted China's first national seminar on rainwater utilization in Lanzhou, a city bordering the Gobi desert. Over the following years, URWH was incorporated into official engineering codes, and the 2008 Olympics provided a perfect platform to showcase these designs. As Yu Kongjian's "sponge city" concept gained traction in the 2010s, and was officially adopted by the government in 2014, URWH became a cornerstone of China's national planning. The current government target is to reuse 70% of rainfall in sponge cities.
According to reports, China's URWH industry, encompassing storage tanks, filtration systems, and other products, reached a staggering 126 billion yuan (£13.5 billion) in 2023, and is expected to grow even further.
But here's where it gets controversial... Reusing rainwater isn't as simple as just collecting and pumping it back into the system. It requires a parallel "grey" water system to keep the recycled water separate from drinking water. This adds complexity and cost to building design, but architects in China see it as a welcome challenge.
Dan Sibert, a senior partner at Foster and Partners, emphasizes that URWH is "absolutely fundamental to the development" of buildings in China. “It’s not a sort of add-on that comes a bit later on.” He sees it as an opportunity to enhance the lives of people using the buildings and their surrounding environment.
And this is the part most people miss... Beyond the environmental benefits, Sibert believes that URWH enhances the user experience by creating a sense of ecological awareness. "If you’re flushing the toilet using grey water, it’s good that people know that," he says. It's about transparency and connecting people to the sustainable practices embedded in their environment.
So, is China's approach to rainwater harvesting a model for other countries facing water scarcity? Could this become a global standard for sustainable urban development? And what are the potential drawbacks or challenges that haven't been fully addressed? Share your thoughts and opinions in the comments below!
