The Rhine as a source of life: PFAS are a threat

For Waternet, the parent organisation of World Waternet, the Rhine is a vital source for the drinking water supply. The river flows into our delta from Germany and supplies water to people downstream. Waternet carefully monitors and purifies the river water in harmony with nature before it is supplied as drinking water to over 1.4 million people in and around Amsterdam.

PFAS spread throughout the entire water cycle

PFAS are man-made substances that enter the environment via production, use, waste streams, emissions and direct or indirect discharges. Examples include non-stick cookware, cleaning products and water-repellent coatings. Because many PFAS are highly persistent and spread easily, they are increasingly being found in soil, groundwater and surface water. This means that PFAS are not only an issue for drinking water treatment, but above all a problem for the quality of our living environment. These substances affect the soil, the food chain and the water sources on which we depend.

Half a litre bottle of syrup

Dutch tap water meets the legal requirements for PFAS and is safe to drink. To illustrate, the National Institute for Public Health and the Environment's (RIVM) advisory limit for PFAS is 4.4 nanograms per litre. That is an extremely small amount: 4.4 billionths of a gram per litre of water. If you were to multiply that amount by the approximately 100 billion litres of drinking water that Waternet produces annually, you would arrive at around 440 grams of PFAS per year. That is roughly the weight of a half-litre bottle of treacle. This comparison shows just how tiny the quantities involved are when it comes to PFAS measurements.

The solution lies upstream

However, the challenge does not begin at the tap, but at the river and thus at the entire water cycle. The cleaner the source, the less complex and costly the treatment required. The presence of PFAS in our environment shows just how interconnected our living environment is. Substances produced, used or discharged in one country can end up elsewhere via the air, soil and water. This calls for cross-border cooperation. After all, borders are human constructs, whilst ecosystems function as a single entity. Only by looking at the entire water cycle – from source to tap and back to the environment – can we protect water sources sustainably.

Water knows no borders

Germany is the dominant source of the PFAS pollution entering the Netherlands via the Rhine. PFAS do not enter the Rhine naturally. The pollution arises from human activities: production and use, emissions into the air, waste streams, historical contamination and direct or indirect discharges via sewerage and wastewater treatment plants. Between Lobith and Nieuwegein in the Netherlands, the PFAS concentration is also set to increase by 5 to 15 per cent, according to the final amendment to the operating licence for Smurfit Westrock Parenco (a paper mill).

Working together to protect water sources

Waternet, together with Oasen, PWN and Vitens, is a member of RIWA-Rijn. RIWA-Rijn monitors and analyses water quality from the perspective of the Rhine as a source of drinking water and raises the issue of source protection with public authorities, policymakers and industry.

This work is concrete. In April 2026, RIWA-Rijn called on the Cologne District Government to implement additional measures against PFAS discharges from the Leverkusen-Bürrig sewage treatment plant, including improved monitoring and treatment of contaminated drainage water. The Rhine does not stop at the border. What is discharged upstream may ultimately reach Dutch intake points.

Prevention is better than treatment

Waternet recognises the problem and is taking action. The company monitors the source, treats the water it abstracts and optimises the treatment process wherever possible. However, additional treatment alone is not a sustainable long-term solution. PFAS are often simply transferred to a residual stream, whilst more complex techniques require greater energy, water and investment.

That is why a healthy water cycle and a source-based approach must take centre stage: reducing production, use, emissions and discharges as quickly and as far as possible; tightening up permits; improving supervision and enforcement; and working towards a broad European ban. Waternet can continue to supply safe drinking water, but must not become the unlimited ‘final solution’ for pollution caused by others. A clean drinking water source begins with a clean river. What does not enter the Rhine does not need to be removed from it.

This article was written in collaboration with Gerard Stroomberg (RIWA-Rijn), Saida Ahyad (Waternet) and Mir Verkaaik (World Waternet).