For a long time, the today Blue Community / Blue City of Berlin in Germany was one of the world’s dirtiest cities. Then a combined sewer system was built, which brought great relief – and became a model for many other cities. But the city still has problems with its water. We translate a longer article by Till Hein on the history of Berlin’s sewage and water treatment published on the website of Einstein Foundation, taken from ALBERT Nr. 9 “Wasser”.
The ‘lovely smell’ of Berlin’s air became famous in the early 20th century thanks to an operetta song. Almost 250 years earlier, however, the smell of the Prussian capital was nothing but disgusting. The Swedish naturalist Carl von Linné noted in 1770 that Berlin could be smelled ‘within a radius of nine kilometres’, and in the 19th century locals were still complaining about the hygienic conditions. “People empty their bedside tables and all the rubbish from the kitchens into the gutters and throw in dead pets”, wrote an administrative lawyer in 1808. In Vienna, the streets were as clean as the corridors of a large house. “In Berlin, on the other hand, one is always wading in dung or dust.”
By 1800, the Prussian capital had more than 170,000 inhabitants. The cesspits in the backyards overflowed. The air was filled with a bestial stench. Rats rummage through the filth. Only occasionally is faecal matter hauled away in horse-drawn carts by ‘dung farmers’ to fertilise their fields. Dirty water flows into the River Spree through open gutters. The slope of these ditches is low. Solids often settle and the sewage backs up. And when it rains heavily, dirty water contaminated with germs floods the streets.
In the spring of 1831, a cholera epidemic broke out. Initially, the disease spread to the poorer districts of the city, where hygiene conditions were particularly precarious. Soon, however, wealthy citizens were also infected. No one was aware that the disease was transmitted by water contaminated with bacteria. By winter, more than 1,400 people in Berlin had died of cholera.
At the time, drinking water came exclusively from wells. Many were located close to privies and cesspits. It was not until the 1850s that the city council built a waterworks and piped river water into homes. By 1860, about 17 per cent of the population had such a connection, and five years later the figure was 40 per cent. Flush toilets are now being installed in homes – and the overloaded gutters are overflowing even more.
Finally, King Frederick William IV of Prussia realised that the sewage system was also in urgent need of modernisation. He consulted none other than Alexander von Humboldt, who as a young man had managed mining projects in Bayreuth and was a master miner. The polymath knew that England was far superior to Prussia in terms of technology, including water management. So he had engineers from Berlin travel to London to inspect its sewage system. In the 1860s, the railway engineer and architect Salomon Wiebe developed an ambitious concept: Sewage and rainwater would be collected in underground sewers and discharged into waterways outside the city. Wiebe wanted to rid backyards and streets of dirt and stench, but he also wanted to protect the laundries and the many open-air baths along the city’s waterways – such as the Pfuel’sche Badeanstalt, built on stilts on the Kreuzberg side of the Spree in 1817, where men could earn a ‘diploma in the art of swimming’ by swimming across the river, which was more than 100 metres wide, and back. However, the project was abandoned for financial reasons.

Photo: Berlin Stadtmuseum Foundation Collection The son of the painter and photographer Heinrich Zille jumps into the water at Kochsee in Charlottenburg in 1901. Most of Berlin’s river baths were closed by 1925 for hygiene reasons.
The Prussian capital continues to grow. New factories attracted more and more workers. Berlin was changing from a residential city to an industrial metropolis – and producing more and more waste water. By the mid-1870s, shortly after the foundation of the German Empire, the population had risen to over a million. The city was suffocating in filth and stench.
Sewers against epidemics
By the end of the 19th century, experts already suspected that the lack of hygiene was a health hazard. The respected medical professor and politician Rudolf Virchow investigated possible links with the spread of epidemics. His suspicion that micro-organisms from faeces in sewage could cause infections was confirmed. For this reason alone, he argued for the construction of a modern sewage system. At the same time, Virchow called for a ban on the discharge of sewage into rivers and lakes. Berlin’s sewage had to be purified by a new process before it could be discharged into the River Spree. The method Virchow proposed had already been tried and tested in England: After the initial mechanical treatment, the sewage was allowed to seep into the ground, where sedimentary rock and plants filter out the pollutants, while dung and micro-organisms in the soil break them down. In July 1870, experiments began at the foot of the Kreuzberg. Experts investigated whether irrigation could endanger the groundwater. They found high levels of ammonia, sulphuric acid and nitric acid in the soil, but gave the go-ahead anyway.
Civil engineer and town planner James Hobrecht developed an overall concept: Rainwater and sewage would flow together through underground channels to pumping stations and from there through cast-iron pressure pipes to the irrigation ditches of the sewage fields. For logistical reasons, Hobrecht favoured several self-sufficient sewer networks, known as radial systems. He divided Berlin into twelve drainage areas, each with its own pumping station and sewage field. Rudolf Virchow also supported this concept. In the spring of 1873, the city council agreed.
Former estates such as Großbeeren and Osdorf in the south and Blankenfelde and Falkenberg in the north were acquired as irrigation areas. Hobrecht had the streets dug up. By 1881, the entire centre of Berlin, with almost 10,000 households, was connected to the new sewage system. Soon potatoes, maize, vegetables, grass and other fodder plants – fertilised by human excrement – were sprouting on the sewage fields. Fish are farmed in the secondary clarifiers. In the long term, the sewerage system will relieve the city of polluted water. However, irrigation does not have a good reputation among the citizens. Rumours circulate that diseases spread around such fields. Professor Virchow personally promotes the method on field trips, sometimes catching water in a glass from irrigated fields and demonstrating by taking a hearty sip. Nevertheless, the vegetables grown there are still not very popular.
A success story with drawbacks
The city’s drinking water supply is constantly overstretched. As early as the mid-1870s, the city council had an additional waterworks built on Lake Tegel. Shaft wells were dug to pump groundwater. However, the cross sections of the pipes were too small. Due to the lack of water pressure, taps on the upper floors of residential buildings often only produce a trickle of water. The pressure at the hydrants is also so low that the fire brigade has to draw additional water from wells to extinguish fires.

Photo: Bundesarchiv The city’s streets had to be torn up on a grand scale to make way for the combined sewer system designed by James Hobrecht – as here in Paulstrasse in Moabit in 1883.
Hobrecht’s combined sewer system, in which sewage and rainwater flow through the same sewers, also has weaknesses: During heavy rainfall, excess rainwater – mixed with sewage contaminated with faeces – flows through emergency outlets directly into the city’s waterways. Towards the end of the 19th century, there were several major fish kills in the River Spree. And the sewage fields became increasingly clogged. The system was reaching its limits.
By 1900, there were 15 river bathing establishments in Berlin. By 1925, all of these popular leisure facilities had to be closed for hygiene reasons. But experts still see no alternative to sewerage and irrigation: they agree that discharging untreated sewage into rivers or lakes would be even more harmful. And the huge volumes of sewage need to be moved out of the city as quickly as possible – not least because of the risk of flooding during storms. This was the case on 14 April 1902, when a huge thunderstorm hit at three o’clock in the morning. Despite all the pumping stations working at full capacity, the sewers overflowed, causing massive flooding. The narrow riverbed at the lower end of the Panke could not hold the water, and the foundations of neighbouring buildings in Gesundbrunnen were torn away. In Wedding, a house on Gerichtstrasse collapsed, and parts of the tram embankment on the border between Schöneberg and Tempelhof washed away.
In later days, attempts were made to prevent such dangers by building underground water retention basins. But even in the 21st century, Berlin’s combined sewer system will be overwhelmed by extreme weather.
Meanwhile, the early 20th century saw further innovations in wastewater treatment: Artificial biological processes were introduced. For example, wastewater is fed into a basin filled with rocks or gravel, enriched with oxygen and discharged after a few hours – largely purified. Such plants emit less odour than trickling ponds and require much less space for a comparable performance. In 1925, sewage treatment plants with activated sludge tanks became common: These are bioreactors in which large amounts of oxygen are added to sludge enriched with microorganisms to break down pollutants and contaminants even more efficiently. More and more sewage farms are being closed down. Only a few remained in operation until the 1990s, for example near Großbeeren.
Despite all the difficulties during construction and operation – and despite the fact that Berliners were never officially allowed to bathe in the River Spree again after 1925 – Berlin’s sewage system is a success story. The engineer and town planner James Hobrecht is regarded as its most important creator. But it was also the work of academics such as Alexander von Humboldt, Rudolf Virchow and many other researchers that made its construction possible. As early as 1900, the sewerage system contributed to a significant improvement in hygiene and helped to reduce disease and mortality. Within a few decades, Prussia had more than caught up with England in the field of water management. Historians would later describe the introduction of the decentralised Berlin radial sewer system in Berlin as revolutionary – similar to the invention of the steam engine in England in the early 18th century. Not only were many large German cities to adopt it – Moscow, Alexandria, Cairo and Tokyo were also inspired by Hobrecht’s concept.
But Berlin’s traditional combined sewer system has disadvantages that are becoming increasingly apparent. During periods of drought, precious water flows out of the city very quickly. And when it rains heavily, the sewers overflow and fish die. In the 21st century, Berlin faces another historic challenge, this time in the face of increasing heat and drought. Experts are once again banging the drum for Berlin to be redesigned, as Rudolf Virchow once did. The idea of a ‘sponge city’ is to secure the water supply of the future – and bring the city back up to date.