I just started watching the series and I'm about 4episodes in.
In episode 2 the shopkeeper old guy says:
Since ancient times, coffee is the one thing that ghouls and humans can enjoy.
but in episode 4 when Touka got a piece of meat from a friend, she was in the bathroom drinking water and fighting to keep it in her body.
She didn't instantly vomit from the water but in episode 1 when the protagonist drank milk he did.
So based off of these observations, can ghouls actually drink water & coffee? And if so are there other dietary things that float along this median line of edibility among both races?