[susan53]

Quote thadajirajaras

I like this answers. THank you very much.

So this sentence "I drink not enough water." is correct?

No - I said when it was part of the subject of the sentence. Here it's part of the object, and so again, it's the verb which must be negated. Compare :

Not many people know this.
Subject : not many people
verb : know
object : this

and

I don't drink enough water
Subject : I
Verb : don't drink
Object : enough water