Put the blueberries with the lavender in a carafe or glass bottle. Add the water to both and let them steep for about 6 hours. When serving, top up the fruity water with ice cubes as desired.
Tip: If you take frozen berries, they give off more flavor to the water. If you don`t have enough time to let the water steep, pouring hot water over the ingredients will help. Only then pour the remaining water over the fruit.