At a Firebowl Cauldron, you can make Water Orb without an Alchemist, but need an Alchemist to make the prerequisite item, Water-filled Glass Flask. Since you need an Alchemist to craft all other kinds of Orbs (Demon-fire, Gaseous, Grease) it looks like it was meant that you needed an Alchemist to craft the Water Orb, but the Water-filled Glass Flask was made to require an Alchemiest by mistake instead; likely mix-up of two similar items.
Unless someone meant to suggest that Exiles aren’t smart enough to figure out how to pour water into an empty glass flask. In this case, clearly the Alchemist was meant to be required to fill waterskins, too.