Understanding engagement with a deposit return scheme for reusable cups: A qualitative study on barriers and enablers of cup use and return through the COM-B Model

Single-use plastics are embedded in daily life and contribute heavily to environmental impacts. Circular initiatives such as deposit return schemes aim to curb this problem yet remain under-researched despite their growing popularity. This study explored the barriers and enablers of engagement within a piloted deposit return scheme at University College London (UCL), in which participants paid a £1 deposit on reusable cups, receiving this refund upon return. Nine semi-structured interviews were conducted with UCL students and staff and analysed inductively to identify influences on behaviour, with themes subsequently mapped onto the Capability Opportunity Motivation-Behaviour (COM-B) Model. Thirteen themes were developed and organised under five COM-B constructs: Psychological capability (understanding the scheme; forgetting to return cups), Physical opportunity (cup design; accessibility of drop boxes; posters and instructions), Social opportunity (social interactions regarding the cups), Automatic motivation (habits; positive feelings) and Reflective motivation (perceived ease; perceived usefulness; perceived reliability; perceived hygiene; alternative goals for using the scheme). For example, for the scheme’s uptake, participants reported needing to understand the scheme, as well as perceiving it as hygienic and useful, and having constructive social interactions about it. Accessible drop locations were noted as particularly important for return behaviours, while forgetting cups or using them for other purposes (e.g., mementos) prevented reusable cups from functioning as shared, reusable assets. By applying a behaviour change framework, this study provides recommendations into how circular initiatives can be strengthened, for example, by providing clearer step-by-step instructions, enhancing communication by staff delivering the intervention and offering timely reminders to encourage cup returns. These insights can be used to inform similar schemes aiming to reduce single-use plastic consumption. The work also contributes to the growing body of evidence highlighting the need for strategies to manage packaging items at the sources, such as reducing and reusing cups, beyond recycling initiatives.