Wash and rub the orange with hot water, cut half into slices. Wash the basil, approx. 3 - 4 stalks, depending on size and aroma intensity.
Put the basil and orange slices in a carafe and fill with approx. 1.5 liters of cold water. Let it steep in the fridge overnight.
When the water is used up, the oranges can be refilled 1 - 2 times with fresh water. The basil quickly becomes unsightly, so it is better to replace it with fresh one for a new batch.