Flat vs Carbonated water on a fast?

[kevin]

I want to say I a presentation by Megan Ramos (maybe elsewhere) where she said the fast specifically consisted only salt and flat water while fasting. What if any could be the problem with carbonated water while fasting? I tend to drink quite a bit of unflavored carbonated water fasting or not.

[marklifestyle]

I tend to drink quite a bit of unflavored carbonated water fasting or not.

I, too, use my soda stream to carbonate my water. I have used it successfully on multiple day fasts. Curious. Interested like yourself @kevin to understand the logic behind the statement.