In a medium saucepan bring water to boil
Add blueberries, sugar, and lemon juice; bring back to boil
Reduce heat and let simmer about 20-25 minutes or until has thickened to a syrup-like consistency (it will thicken a bit more once cools)
Add basil and let simmer for another 5 minutes
Remove from heat and let cool; pour into a storage container. Keep refrigerated and should last about 7-10 days.