In a large mixing bowl, cream together the butter and sugar. Add the water and vanilla and mix well. Mix in the flour and pecans.
Refrigerate the dough for 4 hours.
Portion the dough into 48 balls. (Each ball should be 2 teasoons, or a #60 cookie scoop.)
When ready to bake, preheat the oven to 325°F.
Shape the chilled dough into balls and place them on an ungreased cookie sheet. Gently press the cookies down with a glass or a coffee cup to flatten the tops.
Bake for about 20 minutes. Remove the cookies from the pan and transfer to a cooling rack to cool slightly.
Roll the cookies in powdered sugar while they are still warm.