Give city dwellers their waterways to swim in

A grand processional stair leads down the ­waterfront facade of David Chipperfield’s James Simon Gallery on Berlin’s Museum Island, to a platform where the Kupfergraben canal laps against the sharply-hewn white stone plinth. It recalls the romantic canalside entrance of a Venetian palazzo, awaiting gondola-borne visitors, but sadly no boats may stop here. ‘It’s an affectation,’ Chipperfield told me at the opening. ‘A human gesture to suggest the building dipping its toe in the water.’

But one enthusiastic local group is already eyeing the tempting steps and they plan to arrive not in a boat, but in their bathing suits.

Architect brothers Jan and Tim Edler began the Flussbad (River Pool) campaign in the 1990s – a utopian idea to transform this 2km side arm of the River Spree into a swimmable route through the city. For years Berlin’s waterways were peppered with swimming spots, but by 1925 the putrid water closed the last one. ‘Kot d’Azur’ was its nickname – a play on the German word for excrement.

The Edlers’ campaign has gathered such momentum that the group won €4 million from the government and city authorities to pursue the idea, including developing plans for a plant-based filtration system upstream. After heavy rainfall, sewerage can still flow into the river, but generally the water quality is already good enough to swim in, classified as ‘excellent’ by the standards of an EU directive. Last summer, more than 500 swimmers joined the fourth annual Flussbad Cup, when the water was a balmy 20ºC. The sea of yellow bathing caps bobbing past the rusticated base of the Pergamon Museum and Chipperfield’s slender white colonnade resembled a dreamy student Photoshop collage. But the Flussbad swimmers want to make this permanent, pledging to complete the project by 2025, a century after the last swimming spot closed.

Bronzed bodies drifting down city-centre rivers is already commonplace across neighbouring Switzerland, where Basel, Bern, Zurich and Geneva have long embraced their aquatic urban arteries as places to cool off, exercise and generally lounge around along the riverbanks, as a recent exhibition at the Swiss Architecture Museum showed. In Bern, the centuries-old tradition of swimming in the Aare is enjoying unprecedented popularity, while in Zurich the historical bathhouses along the Limmat turn into waterside bars by night. But nothing beats the tradition of Rheinschwimmen in Basel. Pack your clothes into a Wickelfisch rubber bag, plunge in from one of the many riverside steps and let the current sweep you down the Rhine in a 2km panorama of the city.

It was a chemical disaster in 1986 that provided the catalyst for Basel to clean up its river, and see the banks fitted with long expanses of steps for sunbathing and getting in and out. A nationwide ban on phosphates in cleaning agents has significantly improved river water quality – and the torrents of fresh water from the Alps don’t hurt either.

So why don’t British cities follow suit? As temperatures soared to 39ºC this summer, the prospect of a dip in the murky brown Thames had never been more appealing. Architecture practice Studio Octopi has been peddling its elegant Thames Baths proposal since 2014, but it hit the buffers of the Port of London Authority, which says swimming in the Thames is about as sensible as rambling on the M25, due to the extent of river traffic. Undeterred, the architect has shifted its proposal to the Royal Docks, where wetsuited triathletes already plough the loops in summer. The Studio has an enthusiastic backer, but again seems to be struggling against the wall of health and safety. With temperatures only set to get hotter, it’s time our authorities caught up, cleaned up and started to appreciate urban waterways as the refreshing free amenity they could be.