When you wish to roleplay your thirst, DRINK something.
When you wish to roleplay your hunger, EAT something.
FILL fills a drink container with water.
POUR transfers a liquid to a container, or empties one.
You can also pour from an object into something a character is holding.
Eating and drinking are not required actions here — but they do make for
excellent roleplay. See also NIBBLE and SIP.