Preheat the oven to 375 degrees F (190 degrees C). Grease a 9x13-inch pan.

In a large bowl, mix together oats, cake mix, and melted margarine so that it makes nice clumps and there is no dry mix left. Press 1/2 of oats mixture evenly into the bottom of the prepared pan. In a separate bowl, mix jam with water, and spread over oat mixture in the pan. Sprinkle remaining oat mixture evenly over top.

Bake in the preheated oven for 18 to 23 minutes, or until top is lightly browned. Cool before cutting into bars.