In a large bowl,blend sugars,margarine,water,vanilla and eggs until well mixed.Lightly,spoon flour into measuring cup;level off.In a medium bowl,combine flour,baking soda and salt;mix well.Add sugar mixture;mix at low speed until well blended.Cover;refrigerate at least 2 hours for easier handling. Heat oven to 375 degrees.Using about 1 tablespoon dough,press around each candy wafer to cover completely.Place 5 cm apart on ungreased cookie sheets.Top each with walnut half.Bake @ 190ºC or 7 to 9 minutes or until golden brown.