Only a serious idiot would ever try to pour water on that. The beans slide down the wire mesh into the main bean compartment which is otherwise inaccessible.
Some machines have a wire filter like that to stop objects getting into the water tank; users might misinterpret it. I still really prefer the ones where you have to take out a basket, which is obviously not capable of holding water, and fill it with beans. Sealing it and getting the beans is harder.
For a user to misinterpret and pour water on what biot described would require such a fundamental misunderstanding of common sense and what I can only hesitatingly call "physics", that I don't think it is possible to protect the machine from such a user - except, perhaps, to hope that they will be foiled by the doorknob whose operation they must decipher in order to enter the break room.
http://upload.ecvv.com/upload/Product/200801/200631654352537...
Only a serious idiot would ever try to pour water on that. The beans slide down the wire mesh into the main bean compartment which is otherwise inaccessible.