In Switzerland, more than 30,000 different substances are used on a daily basis in innumerable products – pharmaceuticals, cosmetics, cleaning agents or industrial chemicals. Many of these substances find their way – via WWTPs – into surface waters, where they have adverse impacts on aquatic organisms and drinking water resources. To remove micropollutants from wastewater, around a hundred strategic selected WWTPs in Switzerland are to be upgraded in the coming years with an additional treatment step.