WP2 is aimed on the development of a set of novel online sensors for the remote measurement of selected target microplastics, metals and CECs in urban runoff waters. Establishing the initial requirements and specifications for this online monitoring system is the first step for WP2. The main aim of this document is understanding the case studies’ conditions and environment (WP5) as well as the limitations of the technologies that will be used for the system and how it will interact with the AI-assisted platform (WP4) to describe how the online monitoring system should be at the end of the WP2.The deliverable reports the initial information collected from the different stakeholders (case studies’ and AI-assisted platform responsible, mainly, involving in WP4 and WP5) and a preliminary description of the specifications of the measuring devices included in the monitoring system. A fully detailed specifications’ datasheet and user manual will be produced at the end of the WP2 when the online monitoring system is completed and ready to use.