Preheat oven to 350 degrees F (175 degrees C). Line a baking sheet with parchment paper.

Mix whole wheat flour, rolled oats, brown sugar, barley flour, oat bran, wheat bran, nonfat dry milk powder, flaxseed, cinnamon, baking powder, and baking soda together in a bowl. Add honey, water, olive oil, and vanilla extract to flour mixture and mix well; fold in chocolate chips, walnuts, and coconut.

Place dough in the center of the prepared baking sheet and cover with waxed paper. Roll a rolling pin over dough to spread onto the entire baking sheet. Remove waxed paper.

Bake in the preheated oven until set, about 20 minutes. Remove baking sheet from oven and allow to cool slightly for 5 minutes. Slide parchment paper onto a work surface and cut into bars. Transfer bars to a wire rack to cool completely.