The qualitative study examined a pilot scheme in which participants paid a £1 deposit for a reusable cup and received the refund when they returned it. Researchers conducted semi-structured interviews with UCL students and staff, analysed the accounts inductively and then mapped 13 themes onto the Capability, Opportunity, Motivation–Behaviour, or COM-B, model. The findings reflect the reported experiences of nine participants in one university setting rather than the measured performance of the full scheme.

Psychological capability was represented by understanding the scheme and remembering to return the cup. Physical opportunity included cup design, access to drop boxes, posters and instructions, while social opportunity covered interactions about the cups. Automatic motivation included habits and positive feelings. Reflective motivation encompassed perceived ease, usefulness, reliability and hygiene, as well as alternative goals associated with using the scheme.

Participants offered several possible ways to strengthen engagement. The researchers recommend providing clearer step-by-step instructions, having staff communicate the intervention directly and offering timely reminders to encourage returns. Convenient return locations were reported as particularly important, and participants indicated that viewing the cups as hygienic and useful, alongside constructive social exchanges, could support participation. These suggestions emerged from qualitative accounts and were not evaluated as separate interventions in the reported interviews.

The study illustrates how a deposit scheme can involve more than the payment and refund of a financial deposit. It also shows that a cup may not circulate as a shared reusable asset if it is forgotten, retained as a memento or diverted to another purpose. The authors argue that the findings can inform other circular packaging initiatives and support strategies that manage packaging at its source through reduction and reuse, while the small, local qualitative sample limits how broadly the reported barriers and enablers can be applied.

Subject of Research: Qualitative study of barriers and enablers of reusable-cup use and return in a UCL deposit pilot

Article Title: 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

Article References: Warner, I., Allison, A. L., & Schenk, P. M. (2026). 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. PLOS Sustainability and Transformation, 5(10), e0000301. https://doi.org/10.1371/journal.pstr.0000301

Image Credits: AI Generated

DOI: 10.1371/journal.pstr.0000301

Keywords: reusable cups, deposit return schemes, qualitative interviews, behaviour change, COM-B model, plastic reduction, packaging reuse, UCL, environmental behaviour, circular economy, Understanding, engagement