Heat oven to 275 degree F. Grease baking sheet.
With mixer on medium speed, beat together margarine and 1/4 cup confectioners sugar in medium-size bowl until smooth and creamy. Beat in water and vanilla. On low speed, gradually beat in flour. Mix in pecans with a wooden spoon or by hand.
With floured hands, roll 2 teaspoons dough for each cookie into datelike shapes. Place on greased baking sheet. Score top of each cookie lengthwise with a knife.
Bake in 275 degree F oven for 45 minutes. Roll in confectioners sugar while still warm.