[cypher]

I use the 75ml classic mouse bottles & my dwarf hams can manage those fine (plenty big enough for syrians too), they really do drink a tiny amount so it can be hard to tell.
If you are worried any small, shallow stable bowl for water would be ok too, most of mine actually prefer to use a bowl, tea light holders make good water bowls.
You could also put a thin slice of cucumber in the cage.