The UK Young Scientist of the Year award has been won by a woman for the first time.
Hannah Eastwood, 18, from Loreto College, in Coleraine, Northern Ireland, explored how chromium could be removed from drinking water.
This allows tap water to be purified and reclaimed for the steel industry.
Professor Brian Cox, one of the judges for the National Science and Engineering Competition, said: "It's wonderful to witness such enthusiasm and dedication for science. It's left me hugely excited about the future of science in the UK."
The UK Young Engineer of the Year award was won by Andrew Cowan, 18, from Sutton Grammar School for Boys.