Surrey students’ clean water system wins Davidson Inventors Challenge 2025

YEAR 12 students from Surrey have scooped the top prize at the Davidson Inventors Challenge 2025, for their “impressive” water filtration system.

The Davidson Inventors Challenge was launched in 2020 and is hosted by the University of Cambridge’s Department of Chemical Engineering and Biotechnology (CEB) in collaboration with the Association of Science, Technology & Innovation, and IChemE.

The competition, which attracted 150 UK schools, gives Year 11 and Year 12 students the opportunity to use their STEM skills and expertise to develop a technology or system that can support one of the United Nations’ 17 Sustainable Development Goals (SDGs).

H2O Visionaries, a trio from Surrey’s Sutton Grammar School, set out to tackle SDG 6, relating to clean water and sanitation. Their winning system uses physical, chemical, and biological filtration to remove nitrates and heavy metal ions from water, aiming to improve freshwater sources in developing countries like Bangladesh and the Democratic Republic of the Congo.

'Understood the brief'

“They clearly understood the brief of the challenge. I was overall impressed by what they had produced,” said Fraser Lamb, the team’s mentor and senior process engineer. “The research that they put into their solution was very thorough and they had completed experiments as well to try and back up their claims.”

Along with H20 Visionaries, three other teams competed in the final: Quantum Conquerors from Peter Symonds College in Hampshire, StarchPack Systems from ACS International School, London, and Climate Contemplators from King’s College School, London.

The event also including a keynote speech from Fiona Macleod, novelist and professor of process safety at the University of Sheffield.

Macleod said: “I would like to give a huge thanks to the teachers, mentors, and most of all the students, who gave really interesting presentations which I really enjoyed, you all have bright futures ahead of you.”

Visionary water treatment

For their winning design, H20 Visionaries proposed the use of biochar derived from food waste in their primary filtration system. This could be integrated into existing local industries, including waste management for sourcing the biochar, and local farmers, who can use the spent biochar from the filtration process as a crop fertiliser.

H20 Visionaries, also presented a cost breakdown of its system, factoring in energy consumption and storage costs. They projected the combined cost of their system at around US$106, or US$0.35 per person.

The team said: “This cost breakdown shows that as well as being an effective long-term solution, it is financially realistic for someone who may be living off £1 a day.”

As the winners, H20 Visionaries will be invited to stay the night at one of the University of Cambridge’s famous colleges and spend a day at the CEB where they can interact with academics and students who can help develop their clean water system.

Kamran Yunus, associate teaching professor at CEB and academic lead for the challenge, said: “The H2O Visionaries’ solution stood out for its practical application and the clear effort they put into testing their ideas.”

The competition was named in honour of John Davidson, who died in 2019. One of the most distinguished chemical engineers of the 20th century, he is known for his work in fluidisation and for leading the Flixborough inquiry. You can watch the final here.