We have a tomme tippe cup with a straw and its basically in her line of site for the day. She'll go up to it whenever she wants a drink. At meals times, I put it next to her and then pick it up and say, "do you want some?" If she says no, then I'll pop it back down but normally she'll then pick it up herself and take a drink.
The only bottle/cup my LO will use is a fruit shoot bottle, we filled an empty one with water and that worked! Literally tried everything else!
We starting using the tum tum straw cup and thats how he started having more water otherwise other cups he refused it