You can get the complete axiomatization in delrob_strips_wet.pl.
The relevant parts are:
% wet(Obj,B) is the action of wetting the Obj with the water in bucket B preconditions(wet(Obj,B), bucket(B) & autonomous(Ag) & full(B) & carrying(Ag,B) & at(Obj,Loc) & at(Ag,Loc)). addlist(wet(Obj,B),[is_wet(Obj)]). deletelist(wet(Obj,B),[full(B)]). % fill(B) is the action of filling bucket B preconditions(fill(B), bucket(B) & autonomous(Ag) & carrying(Ag,B) & at(Ag,o111)). addlist(fill(B),[full(B)]). deletelist(fill(B),[]). primitive(full(_)). primitive(is_wet(_)). bucket(b1) <= true. holds(sitting_at(b1,storage),init).
Note that the regression planner can find this plan.