What you can do with rainwater

Rain is wet, dirty, annoying. The best thing to do is to let it flow away quickly, into the gutter, into the pit, away. Rain is something to get rid of quickly – right? The Netherlands has traditionally been the champion of keeping water out. But the question is increasingly how long this attitude towards rain can be sustained. Climate change is likely to make it both soaking wet and bone dry more often, increasing the need for buffering: storing water when it’s wet, to use it when it’s dry.

And a serious drinking water problem looms. Earlier this year, RIVM warned that the Netherlands urgently needs to deal with water differently in order to prevent drinking water shortages around 2030. In the hot summer of 2022, some drinking water companies had problems meeting the demand, drinking water company Vitens says it is already experiencing shortages, and in various European countries water regularly no longer comes out of the tap. After the last wet spring, drought is threatening again.

That raises the question: shouldn’t we learn to deal with rainwater differently very quickly?

A growing group of designers, urban planners, citizens and researchers say yes. An important solution to many of the current and future problems will literally fall from the sky, according to them. What can we all do differently with the rain, according to these pioneers?

1. Drink up

“Here, a glass,” says Albert Jansen, board member of the Rainwater Alliantie. Here in the former Rotterdam swimming pool Tropicana, now renamed BlueCity, a breeding ground for sustainable start-ups, is their experimental ‘rainwater bar’. The glass contains rainwater that has been collected, after which it is filtered through a man-sized test set-up of pipes and water tanks. It tastes like nothing: like any other glass of clean water.

“In theory, about 2.2 percent of the rain that falls in the Netherlands every year should be enough to meet our entire water needs,” says Jansen. Yet this is only one of the few places in the Netherlands where experiments are being carried out with this kind of ‘decentralized filter systems’. There is exactly one campsite in the Netherlands where local rainwater may be used as drinking water, the work required for a permit application to be allowed to do so often takes years.

Some pioneers trying off the grid have (often expensive) filter systems on their plots, and here and there are beer breweries that are allowed to use rainwater after filtering to brew their drink. But that is all – indeed – still small beer.

The dune water from, among others, the Amsterdamse Waterleidingduinen is of course also a form of filtered rainwater. But collecting rain locally to drink it yourself hardly happens in the Netherlands. Why haven’t we been drinking much more rainwater for a long time now?

Mainly because it is often less clean than many people think. Precipitation absorbs pollution from, for example, pesticides and exhaust gases, and if it is collected via roofs, also bird droppings, lead from roofing, particulate matter, and more. “Chemical problems that are easy to solve with fairly simple filtering systems,” says Albert Jansen. He mainly sees a large lobby from existing water companies that hinders the transition to drinking rainwater on a larger scale.

But there is more to it than vested interests. The drinking water system in the Netherlands consists of many thousands of kilometers of pipes and pumps, all aimed at getting water from central basins to homes and businesses as efficiently as possible. Even a seemingly simple adaptation such as rainwater for flushing toilets, instead of the purified drinking water that is used now, has so far proved too expensive and too difficult to implement on a large scale.

But due to the imminent scarcity of drinking water, the pressure to change will increase, Jansen expects: “People have always drunk rain, and then suddenly that is not possible? It is not waste, but a valuable raw material.”

2. Make your neighborhood greener

Another example of new ways of dealing with rain can also be found in Rotterdam, in the Zomerhof neighbourhood, also known as Zoho. There are the large black letters ZOHO in a so-called rain garden. Those ‘ZOHO Rain Letters’, designed by designer Bas Sala, are rainwater buffer and meeting place in one. The rainwater that falls on the adjacent Hofbogen, an abandoned railway track, is not led to the sewers but to the letters, a kind of enormous rain barrels. A built-in solar-powered ‘smart’ system monitors the weather forecast via the internet. When a heavy shower arrives, the system releases the water, creating buffer space for the upcoming rain shower. During long periods of drought, the water is retained and waters a green garden. “The rain helps to create a place where it is also nice to have a picnic and play,” says Sala.

In addition to these types of ‘rain letters’, there are ‘rain benches’ in Haarlem, for example, which serve as multifunctional rain barrels, and which you can also sit on. There are also so-called wadis in various places in the Netherlands rain gardens on the rise: they can be found in Nijverdal, Groningen and Amsterdam, among others. Wadis and rain gardens are green places for water storage and buffering, often a kind of green ditches where the rain is stored in the soil and above ground, like a kind of sponge.

The first wadi in the Netherlands was created in Enschede in 1997, but according to Floris Boogaard, lecturer in Spatial Transformations at Hanze University of Applied Sciences in Groningen and consultant at Deltares, there are now more than 1,500 in the Netherlands. The most important thing about a wadi is that the water infiltrates into the ground within a few days, so that it can also store the next shower. They are therefore not ditches in which the water remains.

“What can be improved, and little is happening yet, is designing the wadi in a nature-friendly way,” says Boogaard. They are now often grass ditches, it would be better for biodiversity and soil to put more diverse plants there. You can also use wadis to create green ‘eco ribbons’. An ecoribbon is a connecting zone that connects green areas and uses the rainwater for a continuous green area in a neighborhood or city. “Such an eco ribbon forms a healthy urban climate for humans and animals.”

But do residents want that?

For example, an eco ribbon can also be a pleasant living environment for pests such as mosquitoes. But according to Boogaard, this is not apparent from studies: the rainwater sinks away faster than the mosquito eggs need to hatch.

According to him, much more can be gained by letting residents come up with ideas for the management and construction of these kinds of rain parks in their own neighbourhood. “For example, by having residents plant fruit trees there, you can pick apples and pears with the whole neighborhood in the fall and bake pies with them, for example.”

Some municipalities are experimenting with ways to make money available to local residents, who can then set to work themselves with the construction and management of rain gardens and wadis. In this way, a different approach to the rain can be good for climate resilience, biodiversity, awareness and cohesion in the neighbourhood, is the idea.

3. Play with it

As far as these kinds of creative rain solutions are concerned, things are going remarkably faster in neighboring countries than here, say Bas Sala, Floris Boogaard and Albert Jansen, all three somewhat enviously. In Gothenburg, Sweden, for example: it rains there about a third of all days, it is one of the wettest places in Europe. The city has started the Rain Gothenburg project to become ‘the best rain city in the world’, with smart water collection, green roofs and water playgrounds that are most fun when it rains. There, children can stomp through deep puddles and create river systems or dams in the sandpit.

In addition, Gothenburg has organized an annual competition to have poems cast on manhole covers and there is an art project in which the footprints of polar bears can only be seen in a city square during the rain. Of course, more is needed for the change in thinking about rain, but Göteborg hopes that these kinds of playful projects can help to involve people more in the transition.

In Belgium, too, they are ahead of the Netherlands on crucial points when it comes to dealing with rain differently. In Flanders, the collection and reuse of rainwater has been mandatory for years. Since 2004, homeowners have been required to build a well under their home so they can use the water that falls on their property. There are no such obligations in the Netherlands yet, although national and local governments do encourage the use of a rain barrel, some municipalities even give them away for free.

The question is how long that will remain so optional. The government is working on a ‘National yardstick for a green, climate-adaptive built environment’, which may also include mandatory rain storage for new homes.

Designer Bas Sala compares the change in thinking about rainwater with the energy transition. “With rain we are now where the energy transition was about fifteen years ago.” Initially, too, the need for this was not felt by everyone, the vested interests and existing infrastructure worked against the change – but now there seems to be no way back. And that transition also gained momentum, partly because citizens simply started working with the new possibilities themselves.