How to make pancakes/crepes without eggs nor any liquids besides water?
Given your updated criteria, what about using powdered milk for crepes and pancakes?  Powdered milk tends to be very inexpensive.  You can usually find in in the baking aisle at groceries in the U. S.  The powdered milk will last you for a long time.

You can also get powdered eggs.  Just google for them.

As Martha astutely commented below, look for recipes for pancake mixes that require adding only water and pack those.