Water bottle

#OneLess - Because everything we do touches the ocean 

One Less

Established in 2016 by the Marine CoLABoration, #OneLess was set up as an experiment to turn the tide against single-use plastic within a complex urban setting.


Led by ZSL, in collaboration with Forum for the Future, the International Programme on the State of the Ocean, and the Thames Estuary Partnership, #OneLess worked with businesses, policymakers, innovators and communities to spearhead a change in the way Londoners drink water – from single-use plastic water bottles, to refilling and reusing.

In six years, #OneLess eliminated 9 million single-use plastic items; dispensed 981,000 refills from new drinking fountains; and removed 137,000 bottles from the River Thames in partnership with Thames21 and citizen scientists.


#OneLess is now a wider network achieving positive action every day. It will continue to grow in different ways as pioneering organisations spread their learnings and new approaches evolve for different parts of the globe. Read more about our campaigns, scientific research projects and wider impact on the #OneLess website.


 Watch our campaign video

Refilling from drinking fountain


The ocean supports all life on Earth and its health is inseparable from our own. It provides us with half the oxygen we breathe, supports the livelihoods of billions of people worldwide, and is home to nearly 200,000 identified species. Yet, it is currently under threat – from plastic pollution. 

Experts estimate that up to 14 million tonnes of plastic enter the ocean each year, and by 2050, plastic in the ocean may outweigh fish. Plastic pollution demonstrates how inextricably linked the ocean and climate are - if the ocean can't function, its role in the climate system is compromised. Both crises must be tackled together. 

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After catalysing significant change across the hydration system in London, the experimental phase of #OneLess came to a close in January 2022. To ensure the movement continues to grow in years to come, the #OneLess team created a Roadmap for London, which identifies exciting and achievable opportunities for everyone to further eliminate plastic bottled water in the city. 

They also developed a Practical Guide to using systems change approaches to tackle an environmental conservation issue. This is a free, open-source guide, available to anyone with an interest in replicating and scaling the #OneLess approach in other cities around the world. An Executive Summary is also available.

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Visit the #OneLess website to read more about our project approach, including the #OneLess Pioneer Network; ‘A Message in a Bottle’ ocean tracking initiative; the #OneLess Fountain Fund and Thames Bottle Monitoring programme.Or get in touch with us at: oneless@zsl.org - we’d love to hear from you!


Choose the sustainable way to drink water - go #OneLess today. 

Refill alternatives


Humboldt penguins investigate recycled plastic bottles at ZSL London Zoo
ZSL London and Whipsnade Zoos have removed all single-use plastic water bottles from its shelves, as part of the #...



Project timeline:


People involved at ZSL: 

Heather Koldewey, Fiona Llewellyn, Shauna Jordan, Surshti Patel and Alice Chamberlain.