Simply place the peels and cores of the apples that you have leftover from canning, applesauce, or pie making into a gallon sized jar.
Stir the sugar into 3 cups of the water and pour over the apples
Fill jar with water to about 2 inches from the top of the jar.
Cover with several layers of cheescloth to help keep out bugs, but allow fermenting gasses to escape.
After 6 weeks, drain off the liquid. This will be hard cider at this point. Compost the apple peels/cores.
Store in a tightly capped jar for another 2-4 weeks to finish the fermenting process.
You now have vinegar!