Place blueberries, sugar, and water in a sauce pan. Simmer for 15 minutes. Remove from heat and place in a food processor. Blend till smooth. Strain with a fine mesh strainer over a medium bowl. You will need to use a spatula to move the blueberries around, and press the puree into the sides. You will be left with very little solids. Pour into a jar and allow the puree to cool for about 45 minutes before using it.