水をいっぱいほしいんだけど。

water (esp. cool, fresh water, e.g. drinking water); fluid (esp. in an animal tissue); liquid; flood; floodwaters; water offered to wrestlers just prior to a bout; break granted to wrestlers engaged in a prolonged bout

indicates direct object of action; indicates subject of causative expression; indicates an area traversed; indicates time (period) over which action takes place; indicates point of departure or separation of action; indicates object of desire, like, hate, etc.

amount necessary to fill a container (e.g. cupful, spoonful, etc.); drink (usu. alcoholic); full; one squid, octopus, crab, etc.; one boat; fully; to capacity; a lot; much; all of ...; the entire ...

wanted; wished for; in need of; desired; I want (you) to

yes; yeah; uh huh; negative verb ending used in informal speech (abbr. of negative verb ending "nu"); abbr. of particle "no"; abbr. of particle "ni" (used especially when it precedes the verb "naru")

be; is; indicates past or completed action; indicates light imperative

but; however; although