Harmful chemicals commonly found in drinking water

Harmful and long-lasting polyfluoroalkyl substances (Pfas) are found in groundwater in many places. They have been detected at almost half of the measuring points in Switzerland. The current limit values ​​were exceeded at one measuring point.

Overall, the measurements revealed the detection of 13 different Pfas. The water samples taken in 2021 showed the highest concentrations of perfluorooctane sulfonic acid (Pfos), the Federal Office for the Environment (Bafu) announced on Thursday based on a pilot study by the National Groundwater Monitoring (Naqua).

The acid has been banned in Switzerland since 2021, with a few exceptions. 80 percent of drinking water in Switzerland comes from groundwater. The results are based on samples from more than 500 Naqua measuring points.

According to current knowledge, firefighting foam is an important source of Pfas in groundwater. These were used at fire brigade locations or on training grounds for civil defense, industry, petrol stations and railways. In some cases, Pfas repeatedly entered the ground in these places.

Other sources such as landfills or wastewater also contaminate groundwater with Pfas. PFAs and radioactive residues were found at the old city manure dump in Solothurn, as it became known in September. This leads to unplanned additional costs during the renovation.

The problem with these long lasting chemicals is well known. They are very stable and hardly degradable chemically, biologically or thermally. The Environment Agency is currently investigating whether an action plan is needed to reduce the burden of PFAs on people and the environment.

The reason for this was a postulate by National Councilor Tiana Moser (GLP/ZH). In addition, in response to a motion by State Secretary Marianne Maret (Centre/USA), the Bafu is developing limit values ​​for Pfas for contaminated sites, soil and discharges into water bodies.

The limits of the Drinking Water Regulation apply to Pfas in groundwater. This currently sets limit values ​​of 0.3 and 0.5 micrograms per liter for three individual Pfas substances.

The Federal Council has already issued bans on the most common PFAs with the greatest health risk. Pfas is a group of substances consisting of several thousand chemicals that remain in the environment for a very long time.

PFAs have been produced industrially for decades and can be found in many products due to their water and grease-repellent properties. In addition to firefighting foams, this includes waterproofing agents, breathable rainwear, ski wax and non-stick pans. (saw/sda)