I could swear I saw a drinking fountain once, somewhere along that long corridor connecting the gates but I never found it again and, to this date, I've never drank from it. (I mostly fly Eurowings to other Schengen destinations.) If it really exists, I'm sure there is only one such station past security, or maybe one per airport wing.

And look, in a pinch I'm ready to drink tap water from the airport toilet faucets. I'm ready to entrust my life to that dice roll. But, as a matter of human dignity being inviolable and all that, I would much rather shell out money for an expensive bottle of water.