Per- and polyfluoroalkyl substances (PFAS) have been detected in Swiss watercourses, according to analyses carried out on 12 selected rivers in a pilot study in 2021.
The pilot study conducted in 2021 examined samples from 12 selected watercourses to gain an initial assessment of PFAS contamination. Over a two- to six-month period, samples were collected from 12 sites participating in the National Monitoring Programme for Substance Load in Swiss watercourses (NAWA FRACHT, formerly NADUF), along with four cantonal monitoring sites on large and medium-sized watercourses. All samples were tested for 22 different PFAS.
PFAS detected in watercourse samples
PFAS were detected in all watercourse samples. The total concentration of the 22 PFAS in the watercourses reached a maximum of 0.05µg/l, which is significantly lower than peak concentrations found in groundwater at some locations.
The Glatt, Ergolz and Birs rivers showed the highest contamination levels, with values exceeding 0.01µg/l. The greatest variety of substances were detected in these three rivers and at monitoring sites at Weil am Rhein and Chancy (downstream of Lake Geneva). These catchment areas are densely populated and exposed to intensive commercial and industrial activity. The Rhine, Aare, Limmat, Reuss, Thur, Kleine Emme and Wiese rivers showed average total concentrations below 0.01µg/l. Concentrations in the Inn and in the Rhone near its inlet into Lake Geneva were generally lower.
In total, 12 of the 22 investigated PFAS were detected in the watercourses. PFBA (C4) was particularly widespread in surface water, appearing in 98% of samples. The 2021 data enabled an estimation of the annual PFAS load: for 22 PFAS, this totalled 385kg annually exported by the Swiss rivers Rhine, Rhone and Inn to neighbouring countries.
In parallel with this pilot study, groundwater in Switzerland was also tested for PFAS as part of the National Groundwater Monitoring Programme (NAQUA).
Further nationwide investigations
In 2024 and 2025, an additional monitoring campaign on PFAS in watercourses was carried out at approximately 140 monitoring sites. Three samples were collected at each site as part of the National Monitoring Programme for Surface Water Quality (NAWA TREND) to obtain a comprehensive overview of the contamination situation in Switzerland and identify substances relevant to surface waters. The results of this survey are currently under evaluation.
Since autumn 2024, the loads of selected PFAS have also been monitored in larger watercourses under NAWA FRACHT. Additionally, there are plans from 2026 onwards to expand the monitoring of micropollutants in the NAWA TREND programme at several sites to include selected PFAS.
Further information
Last modification 26.08.2025
