Fever Tree Soda Water blends soft spring water from rural Staffordshire with an exceptionally high level of carbonation. This high carbonation creates a smoother tasting drink and allows them to stay carbonated for much longer than other mixers. Importantly, no preservatives or artificial ingredients are ever used in any of Fever-Tree's products. If three quarters of your drink is the mixer, then you should be using the best mixers. 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.