Peel and slice apples. In a large bowl, toss apples with lemon juice and set aside.
Pour water into a Dutch oven over medium heat. Combine sugar, cornstarch, cinnamon, salt and nutmeg. If using granny smith or other sour apples use an extra cup of sugar. Add it all to the water, stir well, and bring to a boil. Boil for 2 minutes, stirring constantly.
Add apples and return to a boil. Reduce heat, cover and simmer until apples are tender, about 6 to 8 minutes.
If canning, proceed with the next two steps, otherwise you can freeze the pie filling by letting it cool to room temperature then pouring it into freezer safe containers leaving a half inch of headspace. Frozen pie filling can be stored for up to 12 months.
Ladle hot apple pie filling into hot pint jars leaving 1 inch of headspace. Remove air bubbles by stirring gently. Wipe residue off rim of jar, then center lid on jar and apply band until fit is fingertip tight.
Process jars in a boiling water canner for 25 minutes, adjusting for altitude. Remove jars and cool. Check lids for seal after 24 hours. Lid should not flex up and down when center is pressed.
