Yeah! you have to becareful with Revelation. Most of it is symobolic . wormwood first finds his origin all the way back in Deuteronomy 29:18, and literally it means bitterness. There was some kind of a root that was rather bitter and you have the story of how the water turned to wormwood, meaning it was bitter. People couldn't drink it. In Revelation, that symbol is used, it's referencing a star called wormwood, meaning bringing bitterness in the Bible.
Water represents the truth, represents life. There is a corruption of the truth and it's referring to a time period where false doctrines were introduced that corrupted the truth of the gospel that originally was preached by the apostles. It's a counterfeit doctrine, a counterfeit teaching. The word literally just means bitterness. It's connected with a type of bitter root. That's what happened to the living water was polluted by great apostasy in the church during the dark ages. That's why you find that phrase wormwood.