"You want to drink."
Translation:Vous voulez boire.
Verb "vouloir" is constructed with an infinitive (and no preposition).
"Buvez" is a conjugated form of verb "boire", in 2nd person plural, ie "vous".
So, your proposal is wrong and in any event, whether you drink water or any other liquid, the sentence remains the same: "tu veux boire" or "vous voulez boire".