It’s Time We Rediscovered the Sparkle in Tap Water

Here in Germany, we really ought to treat ourselves to a daily glass of tap water poured from a crystal carafe brought to us on a silver platter. This would be an entirely appropriate way to honor the excellent quality of this much neglected everyday resource. Why does anyone still prefer to buy bottled spring water to wash their hair? And where do the so-called “clumps” in the city’s sewer system come from – those long, smelly, tangled masses of waste material that form in the flowing wastewater, blocking the sewage pumps and requiring removal by hand?

As head of the Department of Fluid System Dynamics at TU Berlin, Professor Dr.-Ing. Paul Uwe Thamsen investigates these and a range of other related questions. Using a virtual representation of a pumping station – a so-called “digital twin” – TU Berlin engineers hope to better understand and control the wastewater infrastructure of large cities and rural areas. In their research, they involve both members of the public and their own cooperation partners to incorporate different perspectives.

Professor Thamsen, how – and why – do you integrate citizen science into the research connected to the digital twin of a pumping station?

Everyone needs water – drinking water as well as wastewater. Our research into water infrastructure places us automatically at the heart of something that concerns the population as a whole. In order to understand what’s required of water management, we’ve been treating the needs of society as an essential part of our research from the very beginning. A think tank at the Hasso Plattner Institute, for example, asked consumers directly: “How important is tap water to you?” The survey showed that people take the water supply for granted. Only a few are aware of the infrastructure behind it and of the steps we can all take to help things run more smoothly. Many people would probably love to have a pipeline into their homes supplying them with their favorite beer – in the case of water, we’ve already succeeded, but hardly anyone notices! The question is if this is the case despite the fact, or because drinking water of this outstanding quality just flows from the tap every day?

We go about our research in a very practical way – with the public for the public. Talking to consumers is just as important to us as working with the public institutions and market leaders who put into practice the technologies developed by us under real-life conditions and bring them into the marketplace for all to see. For this purpose, we cooperate with various partners such as Berliner Wasserbetriebe, Siemens AG, Aquanet (the network of the Berlin-Brandenburg water industry), the German Association for Water, Wastewater and Waste (DWA), the German Water Partnership (the network of the internationally oriented German water industry), as well as international universities in Trondheim, Krakow, Dublin, Copenhagen and Milan.

What are the more common misunderstandings that you encounter?

There’s a lack of important information regarding everyday matters. Surprisingly, many still believe that we shouldn’t use too much drinking water. Quite the contrary – saving water makes it more expensive! We need the flushing speed in the water pipes – otherwise deposits, blockages and corrosion occur, and these in turn make costly maintenance work necessary. We should avoid the first spurts of water, especially in the morning or after returning from vacation, and let the tap run for a few minutes to flush the stagnant water from the pipes. Hardly anyone is aware of how little we pay for water: One thousand liters of fresh water, including sewage disposal, costs about four euros – and that’s enough for about eight days!

What about wastewater?

We’re interested primarily in the question of how blockages occur in the pipe system. A major problem in the city’s sewer system is caused by the unsightly, clogging clumps. The most common cause of these accumulations of waste material are wet wipes that people thoughtlessly flush down the toilet. For toilets, there are special wet wipes that disintegrate. Baby wipes, however, don’t, but these are exactly the ones that are especially popular with small children learning to use the toilet. Together with the water companies, we inform consumers of how important it is to use wet wipes that decompose after a short time and can be biodegraded. We actively support the Wasserwerkstatt event, a water workshop offered by Kompetenzzentrum Wasser Berlin gGmbH, to which we invite ordinary members of the public. One well-known drugstore chain has even replaced its home-brand product with a degradable version. But no sooner do we get on top of the problem with baby wipes than we find ourselves facing similar problems with facial tissues and other hygiene items.

Parallel to encouraging changes in consumer behavior, we are therefore currently also developing new technologies for pump systems that enable them to cope with baby wipes and other non-degradable wipes. With a digital twin, the danger of such clumps can be detected at an early stage.

How does a digital system help improve pumping performance?

In a digital system, we map the technical data, parameter settings, and operating and maintenance information of a pumping station. With this digital twin pumping station, we can investigate in a virtual way the interaction of current and prospective technologies. The measures we develop for the wastewater sector based on our findings can be incorporated straightaway into a technical environment that is immediately marketable. This means that we’re not creating a university-lab solution that takes years before being put into practice. To tackle the wet-wipe problem, for example, we now run the pumps backwards to clear them. Our research partner Siemens is the market leader in this field and has implemented our solution directly into the control technology.

With urbanization increasing, and climate change advancing, water management is gaining in importance too. Can the digital twin also contribute something in this regard?

Our digital twin incorporates various data that is generated in real time and leads to savings and optimizations in many areas. Beyond that, networking with other kinds of data, such as weather forecasts, is possible; this data then flows into the operational management of water-relevant plants. Applied to a real pumping station, this means that if, for instance, the weather forecast predicts no rain, the pumps can be operated at lower speed and save energy, because they won’t be required to process rainwater. During heavy rainfall, however, the pumps need to run faster to take advantage of the water reservoirs and clear the roads. If meteorological data is fed into a networked system, the latter can be operated in a predictive manner. In the long run, digitalization saves us costs that would otherwise be incurred in the event of a flooding.

What’s your vision? What do you expect?

Water has always been a matter of great interest to me. The German Working Group on Water Issues of the Federal States and the Federal Government (LAWA) has developed a “strategy for effective risk management in the event of heavy rainfall.” The recommended measures – such as underground rainwater storage trenches, greater biodiversity, unsealed instead of concreted parking lots, rain barrels in gardens – are aimed at national, state and municipal levels in Germany, as well as at private citizens and companies. Water moves in a control loop in which the natural water cycle and human-made influences continuously collide. That’s what makes the dialog between research and society particularly important. Many ideas have a direct impact on society as a whole. For this reason, we cannot expect people just to accept technologies after they’ve been put into practice, but must involve them in a participatory way from the very beginning.


Prof. Dr.

Paul Uwe Thamsen

Organization name Chair of Fluiddynamics – Fluidmechanics in Machines and Systems
Office K 2