I have an 11mo who just WONT drink v much at all. He has a cup of milk when he wakes up (lucky if he drinks half of it) and the same at bedtime (when he drinks even less of it!).
I try to get him to drink with his meals and snacks and when he wakes from naps but he probably only takes 400-500 ml of fluid a day if we're lucky. He eats really well though.
He gets a milky breakfast (porridge or weetabix), loves yoghurt and we make his meals a bit more sloppy with extra water. We've tried different beakers, lids, no lids, straws etc and I'm worried as in the last 48 hours he's lost interest in the milk at all and is getting constipated.
I leave beakers (with lids) around at all times for the children to drink (I'm a CM) None of the children (18mo, 16mo, 3yo) would drink anywhere near enough the required fluid intake at just mealtimes. However with their cups out all the time, they can help themselves (the same as an adult would)