Put the berries together with the water in a large saucepan and stir with e.g., crush with a potato masher and let stand in the refrigerator for a few hours. Then bring to the boil and pour through a coarse sieve, drain well but do not squeeze out.
Pour the juice through a fine sieve into a measuring beaker and add 1.8 liters of water. Pour back into the pot, add the sugar, bring to the boil while stirring and let it simmer for 1 minute.
Fill into sterilized ½ liter bottles and store in a cool and dark place. Store the opened bottles in the refrigerator.
Tip: Infused with water a refreshing thirst quencher, can also be infused with white wine or Prosecco.