Lesser Ury, Bülowstraße am Hochbahn (1922) (image in public domain, via Manfred Heyde at Wikipedia).

Es ist ein Jammer*... Forget your flip-flops, picnic blankets and straw hats. It is wellies and umbrellas this summer in Berlin. While only last year the city was sizzling under merciless rays of unforgiving sun, begging for shade and cooling beverages, in July 2023 the city saw rainfalls of approximately 75 litres per one square metre – that’s over 20 litres more than the median. It is August now and the wet blanket has not been lifted yet. It’s raining cats and dogs.

Luckily, the city’s well-functioning system of stormwater mains, detention tanks and sewers – a system, which whilst still imperfect, has been protecting Berlin from deluge for the past 150 years and is being heavily modernised as we speak – came a long way from the days of knee-deep gutters and regular flooding. And Berlin used to see enough of the latter as it was.

Take the Panke. With winter slowly coming to an end and snow melting along the riverbed, the rather gentle little river arriving in Berlin from the north and mouthing at the Spree at Schiffbauerdamm, tended to lose its grip on itself. The 29-kilometre long Panke – one of Berlin’s six rivers (next to the Spree, the Dahme, the Havel, the Erpe and the Wuhle) – would turn wilder, and wider, and louder, and sooner or later would leave its regular bed, flooding the nearby areas. Elsewhere in the city the situation wasn’t much better. Every heavy outpour was a potential catastrophe. Since until the second half of the nineteenth century Berlin had no proper sewerage system to speak of and Berliners had to rely on pits, gutters and sluices, during heavy rains, most of the rainwater would have ended up sloshing down the streets and courtyards, washing up whatever unappetising matter the above contained straight under your feet.

Flooding in Yorckstraße after the heavy storms over Berlin in April 1904 (here, on the border between Kreuzberg and Schöneberg; elsewhere in the north of the city several buildings collapsed). For 10 Pfennig you could navigate the deluge sat on a horse-drawn cart.

As you can imagine, that was not only highly unpleasant – it was also potentially life-threatening (think typhoid or cholera). For that reason, Prussian physicians, engineers, and social reformers, like Rudolf Virchow and James Hobrecht – to mention just the two among hundreds, if not thousands – raised alarm: without a functioning, reliable sewer system Berlin would soon become a cesspit.

On top of suffering the consequences of rapid population boom without an infrastructure to match, quite a few Berliners also resorted to straightforward cheating. To save the costs of emptying their cesspits – which in often heavily overpopulated tenements would fill up quite fast – the night-pots and buckets were emptied into the up to one metre wide and some 60 cm deep street gutters before their house. Or straight into the river Spree. Plumpsklos (very basic wooden outhouses erected in the courtyards) were the most popular form of a toilet – in 1871, the year when Germany became an empire and King Wilhelm I turned into Kaiser Wilhelm I, this was the most common facility used by around one million Berliners. The city had only 16,000 water closets and in most of them the foul water drains ended either over street gutters or – yes, you have guessed it – over or in the Spree again.

Both, the authorities and the residents were quick to recognise the problem; however, planning and arriving at the solution took decades. Before that happened, among the usual disputes over costs and responsibilities, many plans had been rejected, including the one presented by Eduard Salomon, the architect of the Prussian Ostbahn – Eastern Railway – connecting Berlin and the East-Prussian cities of Königsberg and Eydthkuhnen.

Eventually, in 1873 the construction of the Berliner Kanalisation began. It took over twenty years to complete the system, but when it was ready, it was quite a thing. James Hobrecht’s Radialsystem, with Berlin divided into twelve sections where wastewater could be transported outside the city using a system of brickwork mains, drains, pumping stations and gravitation, was ingenious. The wastewater ended up on one of the Rieselfelder – or septic drain fields – created on the city’s own estates. The latter had been purchased by Berlin outside the city limits especially for that purpose. Seeing how well the system worked, the then independent municipalities and communities such as Charlottenburg, Schöneberg or Spandau followed suit and did the same. Hobrecht’s Radialsystem became known as the highly effective „Berlin System“ and was duly emulated by other cities abroad, like Cairo, Tokio and Moscow to name just a few.

The 1884 map of Hobrecht’s twelve Radialsysteme for Berlin (fromt he collection of Berliner Wasserbetriebe and Water Museum in Berlin-Friedrichshagen).

The generously designed and built mains and sewers – the city was, after all, expected to expand further – could also take in plenty of rainwater from heavy outpours. Next to the sewers transporting household or commercial wastewater, the network was also fitted with rainwater sewers, and later even with massive subterranean tanks for “temporary parking” of the stormwater that would otherwise threaten to flood the streets when the outpour was particularly heavy.

Today Berlin has over 3,300 km of rainwater canals – if you placed them in one line, they would reach Egyptian Luxor. And they are just one element of the system protecting Berlin from the yet again increasing number of floodings: add to it around 1,900 km of mixed sewers that serve that purpose, too. Those are usually the older canals built mostly in the city centre for, first and foremost, household wastewater, but serving as a kind of an emergency or back-up system in stormy weather. The problem is, these sewers cannot be made bigger, or longer, or wider – they were built under Mitte, or Moabit, or Kreuzberg and it is easy to imagine, how tricky subterranean construction in those areas is. It is quite full down there. And the need to find a solution becomes clear with every heavy rain hitting Berlin, when not only the streets and cellars get flooded but when passing under the railway viaducts becomes a risky venture. The internet is full of short videos showing stormwater deluge at Berlin’s U-Bahn stations. Or those showing tens of thousands of dead fish floating on the surface of the Landwehrkanal – another practically annual occurrence, caused by contaminated stormwater flowing from the streets into the canal as well as by releasing contents of mixed sewers into the city’s bodies of water after a particularly heavy summer storms. Oxygen levels in the city canal plummet and the fish suffocate as a result.

Two waterworks employees manually cleaning the rainwater sewers under Hohenstaufenstraße in Berlin-Schöneberg, 1930). Image via Berliner Wasserbetriebe.

The answer to both problems are giant – humongous! – underground stormwater tanks, like the one built under one of Berlin’s most popular city parks, the Mauerpark. It can hold up to 7,500 m³ of stormwater. By 2026 another such facility, lovingly dubbed “Berlin’s largest rainwater butt” – the stormwater detention tank with the capacity of 17,000 m³, will take up its work. It will intercept the excess of stormwater from the district of Berlin-Mitte, preventing it from spilling into the river Spree instead. New concepts are being tested, too – like the one in Berlin-Grünau, in the residential estate known as “Quartier 52° Nord”, where rain- and stormwater falling onto the roofs and the pavements is re-directed into the large open basin. It doubles up as both a landscape feature (a pond) and a natural water-processing facility. The body in charge of rain- and stormwater management in the city, one whose purpose is help it become the Schwammstadt (Sponge-City) of the future, is Berliner Regenwasseragentur (Berlin Rain-Water Agency).

We have every reason to believe that Berlin will be able to deal with this challenge just like it did with similar challenges back in the 19th century. One thing is certain: Herr Virchow and Herr Hobrecht would have approved.    

*Es ist ein Jammer = It’s a crying shame

A shorter, German version of this text was published in my weekly Tagesspiegel column “Aus der Zeit”.