Aquatic Litter Monitoring system uses RGB images and composites from Unmanned Aerial Systems (UAS; drones) cameras along with Convolutional neural networks (CNN) for precise litter quantification and characterisation. The system ingests, stores, analyses and processes litter floating at surface waters in seas, rivers and lakes, and lying at beaches and shores and eventually delivers standardised classified litter data sets, which are fit for environmental management and indicators. With fine-tuned processing methodology, quality-checked training dataset of litter and the adoption of standardised protocols, the system is operational in the iMagine AI platform, providing valuable analysis to local stakeholders and clean-up operations in multiple countries. Comprehensive guidance and training materials are also available to facilitate the adoption of drone-based litter observation and image processing. Resulting litter data sets are important for environmental management, cleaning operations, and contributing to indicators such as the EU Marine Strategy Framework Directive (MSFD), the EU Water Framework Directive (WFD) and the EU Green Deal.