To date, there has been just a handful of site-specific investigations of microplastics in freshwaters, which represent particles with sizes of less than 5mm. At the University of Birmingham, we are pioneering a fundamental system-wide understanding of microplastic behaviour in freshwaters. In the first-ever comprehensive research study carried out in the UK, we will assess how microplastics are transported, transformed and accumulated in river corridors, how they propagate through aquatic food-webs and impact ecosystem functioning and public health. This has been made possible by a four-year Leverhulme Trust project.