English does not have a simple present with a simple present meaning, like they do in French or German. When we say He does not drink water that has a habitual meaning. This is expressed with a specific tense in Irish. As we have lost that tense in Gaelic we use the future continuous or simple future to express this concept:
Cha bhi e ag òl usige
Chan òl e uisge.
(Note that one of these is introduced much earlier in the course then the other, but they are both perfectly valid.)
So whilst the simple present would be accepted in French or German (and indeed the only one that would be grammatically correct) it is not the correct translation in English.