Is it idiomatic to say "He doesn't drink much water at school"?

Question

In my another post ("Have you done a poo?" vs. "Did you poo?") I said

He doesn't drink much water at school.

Is it idiomatic? Does that sound natural? How about other possibilities?

He doesn't remember to drink much water at school.

He usually forget to drink much water at school.

Which one is clearer? Are there other expression appropriate here?

Answer 1

All are OK, except that the third one should be forgets instead of forget.

You could also replace the word much with enough, to more directly say that he is drinking less than he should.