Water: the most important ingredient in your tea

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Apart from the best tea leaves, what's the most important ingredient to create the perfect cuppa? Chemist Andrea Sella shares his brewing tips with Adam Rutherford for 'The Curious Cases of Rutherford & Fry'. Most importantly, Adam discovers what makes scummy tea and how to avoid it. If you have any Curious Cases for the team to investigate send them to: curiouscases@bbc.co.uk Copyright: Topical Press Agency/Getty Images