Wash the oranges and peel. Set the peel aside for later. Remove the seeds from the oranges.
Dice the oranges saving as much of the juice as you can.
Add the oranges, water, sugar and juice from one lemon into the crock-pot.
Using the saved orange peels, remove as much of the orange rind as possible. Add the orange rind to the crock-pot.
Cover and cook for 2 hours on HIGH.
Remove the lid slightly (ajar) and cook on LOW for 6 more hours or until the mixture has a thicker consistency.
Store in freezer safe containers and store in the freezer until used. The marmalade will store in the refrigerator for up to 2 months.