Filtered UK tap water, a touch of lemon juice, and natural blood orange and mango flavourings. That's the formula here, and it's pretty much the same across the Aqua Libra range. What changes is the flavour character: blood orange brings a tartness that mango rounds out with something softer and tropical. The fizz is light rather than aggressive, and there's no sweetener aftertaste to contend with. It's zero calories, zero sugar, which makes it a reasonable swap if you want something with a bit more going on than plain sparkling water.