UK Sport denied its testers were insensitive to religious beliefs. A spokesman said: "In no circumstances would a sportsman or woman be forced to drink water."
Nicolas Anelka and Robbie Fowler will feature in tonight's second-round, first-leg clash with Polish side Groclin.
Anelka was dropped for the game at Southampton, while Robbie Fowler was pictured smoking and drinking in an Essex nightclub.
Manchester City v Groclin, City of Manchester Stadium, tonight, 8.05pm (Live on BBC3)