"Does my child drink the water?"
because it's a question! think of "-il" like adding "does" otherwise you'd be saying "my child drinks water?"
No, at least say: de l'eau. de le > du, de l' > de l'. "Est-ce que mon enfant boit (de) l'eau?"
Wow, this site is filled with errors! I advise you to not continue your French education through this site.
You HAVE to say "de l'eau". Otherwise, you're implying that your son drinks all of the water in the world.