Ulf Miehe, head of process innovation at Kompetenzzentrum Wasser Berlin
«Drinking water is the safest and most tightly controlled»
Ulf Miehe is a leader in the field of innovative urban water management. His work connects cutting-edge research, engineering practice and practical solutions relevant to water policy, particularly in wastewater treatment, reuse, micropollutant removal, risk management and the development of circular systems.
How is safety guaranteed in the management of drinking water?
Maintaining safe drinking water relies on a multi-barrier approach. This means that protection is built into every stage – from the water source to the tap – so that if one step fails, the others ensure the water remains safe.
The main difference between drinking water from traditional sources, such as rivers or groundwater, and water derived from reuse is its quality. The basic principles of water safety remain the same, but in order to reuse water for potable purposes, some additional steps are required, such as advanced treatment technologies and more detailed safety planning.
What does not change are the strict safety standards – reused water must meet the same strict requirements for chemical and microbial safety as all drinking water under the European Union’s Drinking Water Directive. In other words, reused water must be as safe as traditional drinking water.
To what extent can risks in drinking water supply be adequately assessed and controlled?
Risks can be reliably assessed and controlled to levels where the probability of adverse health effects is negligible. The goal is not to eliminate all risks completely, but to ensure continuous monitoring, the application of multiple protective barriers, rapid response systems and effective regulatory oversight. This approach means that drinking water in developed countries is not only safe for human consumption, but is also subject to exceptionally rigorous control.
It should be noted that regulations governing drinking water have evolved significantly over the past 50 years. A recent example is the inclusion of per- and polyfluoroalkyl substances (PFAS) in the new European Union Drinking Water Directive. PFAS, which are found in contaminated water bodies, can pose serious health risks, which is why regular regulatory updates are essential. However, the use of advanced treatment technologies – such as reverse osmosis – reliably reduces these compounds to levels well below the limits set by the Directive and, in many cases, even below the detection thresholds of modern laboratories.
What is the best way to communicate risks to society?
Communicating the risks associated with drinking water is just as important as managing them technically. The way information is shared can make the difference between building trust and sowing doubt. The most effective way to talk about drinking water safety is openly, clearly, consistently and responsibly, establishing genuine dialogue with the community.
Will citizens be able to clearly understand the risks – or lack thereof – associated with the AIGUANEIX project?
This is a timely and sensitive issue – drinking water reuse projects are often affected by what is known as the luck factor, even when they are scientifically safe. Public understanding of risk depends largely on how a project is explained and experienced.
There are three main challenges. The first is the perception gap: Even if advanced treatment removes pathogens and chemicals to safer levels than many natural sources, people may still associate potable reuse water with the idea of a f lush toilet, which creates a sense of unease. The second challenge is the risk–trust relationship. Scientific evidence shows that well-designed potable reuse systems can be as safe, or even safer, than conventional water supplies. But without trust in the water companies or public authorities, public acceptance is unlikely. The third challenge is the invisibility of safety. Citizens cannot see pathogens or chemicals, so reassurance must come from the transparency and trust generated in communications.
Not everyone interprets technical risks in the same way – for some, feelings of discomfort or disgust can outweigh scientific evidence. Ultimately, risk perception depends more on trust, values and emotions than on technical details. Pilot projects such as AIGUANEIX are highly effective in building confidence. Visiting pilot plants, observing treatment processes or even taking part in water-tasting events allows citizens to experience reuse in a tangible way.
In conclusion, citizens can understand that potable reuse is safe – but only if communication is transparent, consistent and participatory, if risks are explained in clear, accessible language, and if trust is built through independent oversight and community involvement.
«Potable reuse requires advanced treatment technologies and detailed safety planning, even though the resulting water meets the quality standards required by drinking water regulations»
«Risks can be reliably assessed and controlled to levels where the probability of adverse health effects is negligible»
