Sparkling water breaks a fast?
I really like sparkling water drinks that have no sweeteners in them.
My favorite is Aha! Blueberry pomegranate, or Topo Chico in Twist of Grapefruit.
Since there’s no sweeteners, there’s no calories
They might take some getting used to since most people (particularly Americans) associate carbonation with sweetness, but during a fast, these kinds of drinks are phenomenal.