PREHEAT oven to 350°F. Combine flour, sugar, baking powder, baking soda and salt in large bowl; set aside. Beat eggs in medium bowl with wire whisk until foamy. Add margarine, orange juice, orange zest and water; mix well. Add to flour mixture; stir just until blended. Stir in walnuts.
SPOON into greased and floured 9x5-inch loaf pan.
BAKE 50 min. or until toothpick inserted in center comes out clean. Cool in pan 10 min. Remove from pan to wire rack; cool completely. Cut into 16 slices to serve.