Add the water, sugar, cornstarch*, cinnamon, and nutmeg, to a large stock pot.
Cook over medium high heat until sauce has thickened. Add the lemon juice.
Fill the hot sterile jars with the freshly cut apple slices. Pour the hot sauce mixture into jars until 1" from the top.
Cover with sealing lid and cap. Process in a hot water bath for 20 minutes
Disclaimer: According to documentation that I have read, cornstarch should not be used in unapproved recipes for canning. My mother made this pie filling recipe for years and I have made it the same way myself. I have always used cornstarch. However, if you have concerns about using cornstarch in canning pie filling, please use the appropriate substitute of Clear Jell for cornstarch.