Fever Tree Sicilian Lemon Tonic Water is Fever-Tree's re-invention of Bitter Lemon. A delicious and sophisticated drink made using naturally sourced quinine from the bark of the fever tree in the Congo, blended with the finest Sicilian lemon oils used in Fever-Tree Sicilian Lemonade. Importantly, no preservatives or artificial ingredients are ever used in any of Fever-Tree's products. If three quarters of your Gin & Tonic is tonic, then you should be using the best tonic. This is the attitude Fever-Tree brought to the craft of their original Indian Tonic Water and a standard they continue to apply across their range.