Rinse and drain the blueberries. Pat dry. Add blueberries, water, lemon juice, and arrowroot powder to a saucepan and heat on medium high for 5 minutes.

Puree the mixture in a blender or food processor. Return to the saucepan and bring the mixture to a boil over medium heat.

Decrease the heat and simmer until the mixture thickens, approximately 25-35 minutes. Stir every couple minutes, scraping the sides and bottom of the pot to avoid sticking. When you can draw a line through the center of a pan and it doesn't immediately fill back in, the jam is done.

Store the jam in a mason jar for use within a few months. If you'd like to store the jam longer, you will need to go through the canning process.