Combine water, lemon juice, and cinnamon in a large bowl; stir to mix.
Cut each apple in half then slice each end off the apple (the stem and butt). Slice the remaining apple into approximately 3/8″ thick slices, making the slices as even as you can. Use a mandolin if you have one. (Do not slice too thin or the apple will stick to the dehydrator.)
Repeat for the remaining apples. Place cut apples into the lemon water, stirring so each apple is coated with the water. Let soak for 8-12 minutes, stirring occasionally (this step is optional).
After soaking, place apples in a single layer on dehydrator trays. Set the temperature for 145F and allow it to run for 8-12 hours, testing at the 8-hour mark for doneness. Apples should be hard and crunchy without any moisture. Dehydrate apples longer if they are too chewy.
Store in a sealed container.