#OneLess was established in 2016 with the aim to reduce and ultimately eliminate single-use plastic water bottles in London at source. London is an estuarine city, directly connected to the ocean via the River Thames, and our actions in this city profoundly impact the ocean.
The River Thames is London’s very own haven for wildlife, but in 2019 the Thames was identified as having one of the highest levels of plastic pollution across all UK rivers.
Research from BRITA in 2016 showed that Londoners purchased an average of 175 single-use plastic water bottles per person every year. That’s over 1 billion bottles annually city-wide!
Since #OneLess launched six years ago, we have catalysed impact across multiple levels of London’s hydration system to tackle the issue of single-use plastic pollution.

As we close the final year of the #OneLess experiment in London, we’re looking to diversify the reach of our approach by sharing our learnings and experience with other change-makers around the world. This year, we’ve been busy creating #OneLess – A practical guide for tackling ocean pollution at source to support and empower others in applying systems change approaches to their own environmental challenges. This practical guide will take the reader on a step-by-step journey through themes such as collaboration, boundary setting, designing interventions and sustaining lasting change.
In September 2021 we hosted online webinars to officially launch the #OneLess practical guide with a global audience. The webinars catalysed discussions around systems thinking, stakeholder engagement, driving policy change and surfacing ocean values, with great contributions from our attendees spanning 45 cities worldwide. Our webinar recording can be viewed here. Please feel free to download, watch and share with colleagues and networks that would benefit from learning about #OneLess London.
For a very practical and effective model that we believe is highly applicable to a wide range of contexts and cultures all around the world, please take a look at our #OneLess practical guide. If you are interested in using the #OneLess approach to tackle your own environmental challenge or want to share your experiences, we’d love to hear from you! You can reach us at oneless@zsl.org or via our Twitter @OneLessBTL or Instagram @onelessbtl.
Stephen Harris
Marine and Freshwater conservationist at ZSL