Antibiotic-resistant bacteria and antibiotics are excreted in the urine or faeces. They pass through the sewer system into the wastewater treatment plants (WWTPs). The 700 or so WWTPs in Switzerland filter out up to 99% of the resistant bacteria, meaning that few resistant bacteria enter water bodies (rivers, lakes etc.) in the effluent of the WWTPs.
Further discharges into surface waters can be caused by runoff from the soil after heavy rains. WWTPs and municipalities need to collaborate closely to minimise these rainwater-induced discharges of untreated wastewater into rivers and lakes. This would also reduce the seepage of antibiotic-resistant bacteria from slurry and manure in the fields.
Like many other drugs and chemicals, antibiotics are not completely eliminated from wastewater by the WWTPs, and can have a negative impact on aquatic organisms. In order to improve wastewater treatment in this area too, selected WWTPs in Switzerland are currently being upgraded and modernised to improve their effectiveness in removing numerous micropollutants, including resistant bacteria, from the water. In the medium term, this should reduce the occurrence of antibiotic residues and resistant bacteria in the water bodies…find out more