The objectives of this project in brief are: (a) to provide information on the presence and potential formation of selected emerging pollutants and their transformation products (TPs) throughout the water supply system of EYDAP S.A. (water sources, treatment, distribution network), (b) to elucidate the degradation pathways and produced TPs of selected emerging pollutants using advanced oxidation processes (AOPs) and finally (c) to provide a useful dataset of water quality data and register the main risks in the water supply system, enabling the initial formation of a Water Safety Plan (WSP) for organic pollutants and their TPs. So far the fellow has achieved to develop methods for the reliable determination of organic compounds in the water supply system of EYDAP, including: (a) markers of sewage pollution for surface waters, using SPE-GC-MS /MS and SPME-GC-MS/MS, (b) cyanotoxins (CTs) and related cyanobacterial metabolites in surface water, biomass and higher levels of the food chain (fish tissues), (c) taste & odour compounds (T&O) present in surface water, applying non-targeted and targeted screening using HS-SPME-GC-MS and (d) several disinfection byproducts (Haloacetic Acids HAAs), using direct LC-MS/MS. The fellow has also studied the formation of TPs from representative compounds of emerging pollutants (cyanotoxins, T&O, dichlorophenol, etc), using AOPs such as γ-radiolysis, sonication, photocatalytic degradation using TiO2 (suspension or immobilized surface), and the role of various individual reactive oxygen species (ROS) in the degradation mechanism. A database of organic compounds posing as potential risks to the water supply system has been created and is constantly being updated, incorporating mass spectral data and physicochemical properties of organic pollutants, including CTs and cyanobacterial metabolites, T&O, HAAs and oxidation products of selected pollutants.