Preheat Oven to 350 degrees and lightly grease a 9x13 baking dish
Peel and slice apples, layer in greased baking dish
Mix water, vanilla, and lemon juice and pour over apples
Dust apples with cinnamon and sugar
Cut brown sugar, flour, butter and oats together until crumbly mixture is formed, sprinkle on top of apple mixture
Bake at 375 degrees for 45-50 minutes. Serve warm with vanilla ice cream