A weird thing has been happening recently. Science articles and posts have been going viral – and about rainwater capture innovations, no less – but they’re fake. AI created for clicks. Two recent examples, both purportedly from Singapore, are of rainwater capture park benches (the plants positioned precisely where you’d plant your feet are a bit of a giveaway). And similar benches with moss cushions (imagine the wet bum you’d get from that). The former was liked on LinkedIn almost 3,000 times. It is also a very good idea, if you ignore the planting scheme. The latter (2.8k likes on Instagram) is clearly a soggy bottom of an idea.
Warning: AI slop. But are they onto something?
But both examples show there is huge interest in rainwater harvesting and ‘biophilic design’ (integrating natural solutions into the built environment) – it’s only ‘click bait’, after all, if it’s popular enough to click on. And the good news is, there are plenty of real-world, non-AI examples out there. Here’s a run-down of some of my favourites.
The Bosco Verticale (Vertical Forest), Milan, Italy
The Bosco Verticale (Vertical Forest). Photo by Daniel Seßler on Unsplash
These very-much-not-AI vertical forest apartment blocks have existed in Milan since 2014. The Bosco Verticale (Vertical Forest) is a complex of two, 27-floor residential skyscrapers designed by Boeri Studio. Built in the Porta Nuova district of Milan, the greenery is no window dressing. The exteriors are planted with over 700 mature trees, 5,000 shrubs and 15,000 perennials and climbing plants; the buildings take up just 1,500m2 of ground space, yet provide the neighbourhood with the equivalent of 20,000m2 of forest and undergrowth – the planting and irrigation have been integrated into the infrastructure and design of the building. The largest single tree when planted was 9 metres (30ft) high, weighing 820kg (1,800lb), but over ten years on several are now above this height. In the hot Italian summer, heat inside the building is reduced by an incredible 30°C purely due to the vegetation, eliminating the need for air conditioning. The plants and trees draw on and capture rainwater directly, topped up by a solar-powered groundwater pump (no municipal water supply is needed). The architects Boeri Studio have since rolled out the design in several other cities worldwide. Trudo Vertical Forest, in the Dutch city of Eindhoven, is made up of 125 apartments designed for low-income users, contains four rainwater collection tanks housing 20,000 litres each. Every apartments includes an external terrace with one mature tree, 20 bushes, and rainwater capture linked to the centralised tanks.
Upcycled musical instruments!
Photos by Oliver Guhr on Unsplash
In the Kunsthofpassage, a series of artist courtyards in Dresden, Germany, one building in the ‘Courtyard of Elements’ is adorned with a unique water-capture installation. Created by sculptor Annette Paul and designers Christoph Rossner and Andre Tempel (who actually live in the apartment building itself), this piece was inspired by Rube Goldberg Machine, converting rainfall into a spectacular orchestral display. Rainwater channels through a series of trumpets, chimes, and other re-purposed and re-imagined musical instruments. Supposedly it also makes a ‘soundscape’ during rainfall too, though in the videos on YouTube it mostly sounds like plain-old rain (see here – though skip to 50 seconds in to get beyond the person talking over it).
An inverted roof, Spain
© Herreros Arquitectos
A typical pitched roof is pretty good for rainwater capture, but it creates multiple exits and collection points for rainwater gutters. But what if you inverted it, creating just one – essentially turning the house’s roof into one big funnel? That’s exactly what Madrid architects Herreros Arquitectos did for ‘Pebe Cobbo House’. Converting an off-grid old Shepherd’s Hut in a dry rural region, it was essential to maximise natural resources wherever possible – and rainwater in particular. The structure consists of a central load bearing wall, acting as a gutter to catch rainwater, which feeds into a large purpose-built cistern.
© Herreros Arquitectos
Rainwater swimming pools, Hawai’i
Source: The University of Hawai'i at Manoa, College of Tropical Agriculture and Human Resources, Department of Natural Resources and Environmental Management
Rainwater harvesting in Hawai’i is big, in more ways than one. Firstly, everyone does it.
A survey of rural Hawaii Island communities on rainwater catchment found that nearly 90% of respondents used harvested rainwater as both potable water and for bathing (disclaimer: this is something Water Matters cannot condone without a very high-spec filtration system!). According to the official Guidelines on Rainwater Catchment Systems for Hawai’i, an estimated 30,000 to 60,000 people in the state of Hawai‘i are dependent on a rainwater for their water needs. Many do this using free-standing, high-sided swimming pools. The Guidelines state, “These pools are the most common type of rainwater catchment storage tank in use now. The greatest advantage of swimming pool tanks is low cost. Also, homeowners can install them without professional help, and they are readily available from various sources including discount stores”. While the following video is from mainland US, not Hawai’i, it shows in detail how such systems look and work:
Potsdamer Platz, Berlin
Photo by Darko Pribeg on Unsplash
Graphic of the Potsdamer Platz cisterns © Atelier Dreiseitl
Rainwater capture typically comes down to how large your surface area is. A shed roof is good, for example; a house roof – or as we’ve seen, an inverted roof – is even better. But an entire city centre square is better, still. Since it was reconstructed in 1998, Potsdamer Platz in Berlin has five underground rainwater cisterns with a total volume of 2,600 m3, of which 900 m3 is reserved for extreme rainfall. The roofs of the office buildings that surround it as well as the open square itself all feed into the cisterns (the roofs are 60% covered with green vegetation, so that rainwater is naturally slowed and filtered) and then reused for toilets, irrigation, and a central pond and water feature. The combined area is approximately 1.2 hectares (approximately 2 football pitches). As well as saving water they also greatly reduce flooding: the retention, including the emergency overflow cistern, have meant that larger volumes of rainwater have only be discharged into the nearby Landwehr Canal an average of three times every decade.
Sahel moon ponds
Half moons in the Maradi region of Niger. Source: World Food Program
The Sahel is an extremely arid region located in central Africa undergoing catastrophic desertification due to drought, overgrazing, deforestation and climate change. In recent years, however, a green miracle has been turning this situation around. An ancient technique of small ‘half moon’ ponds – also called “zai pits” – has been revived. Using hand tools, the soil is dug to around 30cm deep into a semi-circle or ‘half moon’ shape, typically about four metres across. When any precious rain falls, the contours catch the rainwater, prevent runoff and allow it to infiltrate the soil. This brings greenery back to the desert and allows drought-resistant crops such as sorghum and millet to be planted. In Niger, The World Food Programme (WFP) has been implementing half-moon planting projects since 2014. Just five years into the scheme, over 400 households had restored approximately 3,000 acres of land. Kenya’s Masaai community are also now using the technique. Maasai conservationist Lanoi Meitiekini explained to the BBC, “these are our solution, half-moons… that capture rainwater, which seeps into the soil… We started digging with the NGO, Just Dig It, in 2016. Since then, we have restored 3,000 hectares of land, the equivalent of 6,000 football pitches.” (Potsdamer Platz suddenly seems rather small in comparison!). Half moons have been so successful they now form part of Africa’s ‘Great Green Wall’ initiative, which began in 2007, which aims to restore 100 million hectares of land, providing food and water security for millions of people, by 2030.
One thing the AI slop generators at the start of this article got right is that Singapore is indeed the home of rainwater harvesting innovation. Due to the density of its population and lack of groundwater, Singapore is amongst the most water-stressed countries in the world. However, there is no lack of rainfall. Capturing and reusing rainwater has therefore long been part of the country’s official water strategy. Rainwater that falls within the water catchment is collected and channelled via a network of more than 8,000 km of drains and canals, to 17 reservoirs for storage. Changi Airport collects and treats the rainwater that falls on the runways, which accounts for 28 to 33% of its total water used. But perhaps most striking of all is Khoo Teck Puat Hospital. Designed to be ‘forest-like’, Living Future describes “Greenery extended from the central courtyard to upper levels of the buildings and down into the open-to-sky basement, creating the impression of architecture deeply enmeshed in a garden.” The total surface area of horizontal greenery is almost four times the size of the land that the hospital stands on. There’s even a rainwater-fed waterfall. Aluminium fins along the building’s walls channel the wind and rain, capturing rainwater and cooling the building, which reduces energy use by 50%. Chief architect Chris Johnston explained to RMJM.com taking advantage of Singapore’s high precipitation was key to the design.
Permeable paving
Image: Hull Daily Mail
One of the big problems in modern towns and cities is the coverage of impermeable roads and pavements causing flooding when extreme rainfall hits. Not only is it a flooding problem, it’s also water lost that could have been used in times of drought – or could naturally recharge the groundwater aquifers below. Climate resilience, therefore, requires us to make our urban areas permeable again. A street in Hull recently underwent a radical transformation as a part of Hull City Council's £23m flood resilience project. Rosmead Street in East Hull ripped up the tarmac and replaced it with a permeable road. The design used interlocking bricks, with gaps just large enough for stormwater to seep through. Over 300 properties in the street were also given new guttering and re-laid pavements. Many cities are now undertaking similar schemes internationally.
DIY on-the-cheap
But weird and wonderful rainwater capture doesn’t have to be fancy or expensive. Got an old barrel or even a water butt, but no roof? No problem! On my travels for my book I saw repurposed plastic barrels, even buckets and cooking pots lined up beneath the lip of corrugated iron roofs during a downpour. When I moved into my own house in Oxfordshire, before I installed my water butts, I had been known to use a water-proof table cloth precariously positioned between garden chairs, pinned down with bricks and clothes pegs, leading into a large builder’s bucket. Turns out I’m not the only one. The examples above from Australia and Sudan show how all you really need is a tarp, or a large sheet of plastic, some poles or branches, and ideally a barrel to funnel it into. Amazingly, the idea has even been commercialised as ‘rain saucers’ – think the cone-of-shame that vets put around dogs, but put ontop of a water butt or barrel. As this article has shown, rainwater capture is all about maximising your surface area – and while bigger is better, it’s also true that a little can go a long way.
But sometimes the best innovations are the ones we’ve never heard of. Have you come across any weird or wacky rainwater harvesting techniques on your travels? Or have you erected any DIY contraptions in your own back garden, apartment balcony or workplace? We’d love to hear from you at [email] – and the best ones may well get discussed on an upcoming podcast.
