Spread pecans in a single layer on a baking sheet and toast at 375° for 5 minutes; watch carefully to avoid burning pecans. Set aside to cool. Cream the butter and powdered sugar together until light and fluffy. Add vanilla and beat again. Thoroughly mix in the water and flour, then add chocolate chips and pecans. Shape into small balls, approximately 2 teaspoons of dough each. Place on an ungreased baking sheet and bake at 300° for about 20 minutes. While still warm, roll cookies in powdered sugar and place on cookie rack to cool.