The overall aim of the "Clear Waters from Pharmaceuticals" (CWPharma) project is to provide guidance on how to reduce the load of active pharmaceutical ingredients (APIs) entering the aquatic environment and especially the Baltic Sea. Even though different methods for reducing the amount of APIs entering the wastewater exist and, thus, "end-of-pipe" measures are also necessary. API usage cannot be completely avoided. Municipal wastewater treatment plants (WWTPs) are relevant point sources of APIs as they treat the wastewater from public households, hospitals, and industry of the connected catchment area. However, conventional "state-of-the-art" WWTPs can only remove APIs that are either easily biodegradable and/or absorbable to activated sludge, whereas others can pass the treatment process with no or only minor reductions. Therefore, reduction of a broad range of APIs can only be achieved by using targeted advanced wastewater treatment (AWT) techniques, such as ozonation or application of powdered and granular activated carbon. All of these technologies for API removal are already used at full-scale WWTPs and have proven their practical and economical suitability. This guideline is meant to provide an overview on how to plan, start, and operate AWT technologies for API elimination. The recommendations are based on the experiences and results from the CWPharma project, but also on the available knowledge from Germany and Switzerland, which is collected and distributed by competence centres such as the German Micropollutants Competence Centre Baden-Württemberg (KomS) Verfahrenstechnik Mikroverunreiniungen and the Swiss Plattform as well as by expert groups from the related water associations. Membrane separation via dense membrane such as nanofiltration (NF) or reverse osmosis (RO) was not considered in this guideline, as both technologies produce a brine with high API concentrations. At coastal WWTPs, this brine might be discharged directly to the sea in order to protect fresh water ecosystems, but this would not reduce the API load to the Baltic Sea. Thus, the brine also requires treatment, which makes this approach less economical in comparison to the other established API removal technologies.